LTE IMS Server

1 Introduction
2 Features
3 Requirements
4 Installation
5 Configuration reference
- 5.1 Configuration file syntax
  - 5.1.1 JSON merge rules
- 5.2 Properties
  - 5.2.1 User database options
6 Remote API
7 Command line monitor reference
8 Log file format
9 Change history
10 License
Abbreviations

1 Introduction

LTEIMS is an IMS standalone simple server. It has a built-in P-CSCF, I-CSCF, S-CSCF, HSS. It also allows SMS handling including SMS over SG by connecting to the Amarisoft MME.

2 Features

Implements P-CSCF with built-in I-CSCF, S-CSCF and HSS.
Support of SIP protocol.
Support of MD5, AKAv1 and AKAv2 authentication.
Support of ISIM cards using the XOR, Milenage or TUAK authentication algorithm.
Support of IPsec (ESP/transport).
Support of voice, video calls: MO and MT.
Support of voice echo test.
Support of hold.
Support of SMS (GSM 3.40) using SIP MESSAGE and SMS over SG.
Support of IPv4 and IPv6.
Support of precondition and dedicated bearer using Rx interface or N5 interface.
Support of emergency call.
Configurable user database.
External authentication using Cx interface.
Command line monitor.
Remote API using WebSocket.

3 Requirements

3.1 Hardware requirements

LTEIMS can run on the same PC as the Amarisoft eNodeB if a simple and compact solution is needed. Otherwise, any reasonnably recent PC with at least one Gigabit Ethernet port is acceptable.
A VoLTE compatible UE is necessary (See VoLTE Call, note that it may depends on UE).
A test USIM with ISIM application should be plugged into the UE. IMSI and secret key must be known. A standard USIM may also work but it depends on the UE implementation.

3.2 Known compatible UE

The Amarisoft IMS server has been tested with the following UE models:

Samsung S5
LG MS870

3.3 Software requirements

A 64 bit Linux distribution. Fedora 39 is the officially supported distribution.
The following distributions are known as compatible:
- Fedora 22 to 39
- Cent OS 7
- Ubuntu 14 to 22
Your system requires at least GLIBC 2.17.

4 Installation

The network access thru the Gigabit Ethernet port must be correctly configured.

LTEIMS can be run directly from the directory when it was unpacked. No need for explicit installation.

4.1 Fedora setup

If you want to use SMS over SG with the Amarisoft MME or precondition with QoS, you need support of SCTP protocol for which the necessary packages are not usually installed. In order to install them, do as root user:

Fedora

dnf install lksctp-tools kernel-modules-extra

Ubuntu
```
sudo apt-get install lksctp-tools linux-image-extra-3.13.0-24-generic
```
Note that linux-image-extra package name may differ depending on your kernel version.

To verify that SCTP kernel module is running, do as root user:

checksctp

If it reports that the protocol is not supported,

check if you have a /etc/modprobe.d/sctp-blacklist.conf file
edit it to comment the ’blacklist sctp’ line

Then reboot the PC in case the Linux kernel was upgraded too.

4.2 License key installation

LTEIMS needs a LTEMME license key to run. Please refer to the ltemme documentation.

4.3 Initial testing

Edit the file config/ims.cfg to set the address of the SIP interface. Normally it is the address of the Ethernet interface that will receive SIP packets.
You can keep the current config if you use it with the Amarisoft MME and its config/mme-ims.cfg config file.
Start the program as root with:
```
./lteims config/ims.cfg
```
[The root access is only needed if you want IPsec support.]
The command line interface is used to monitor the operation of LTEIMS and to change the logging options.
Use help to get the list of commands and quit to stop the program.
Use users to list the user database and registering state.

4.4 Samsung S5 configuration

Your UE must run at least Android 5.0 (Even if Android 5.0 is installed, try to update software (several times) as a sub-release is necessary).
If not, please update it.

To check your UE is configured for VoLTE, please go to Settings/More networks/Mobile networks of your handset and check VoLTE Call is checked:

We assume you are using the system with Amarisoft MME and config/mme-ims.cfg config file.
As there are two PDN defined, you must add them to the UE.

Go to Settings/More networks/Mobile networks
Turn on Data roaming
Check VoLTE Call (If not present, it means your device is not up to date or does not support VoLTE).
Go to Network operators, search for networks and select Amarisoft network.
Go back to Mobile network.
Add the first APN with the following parameters:
- Name = Internet
- APN = internet
- APN type = default
Save it and select it.
Add second APN with following parameters:
- Name = IMS
- APN = ims
- APN type = ims
Save it and do not select it (This APN may not be displayed).
Reboot your phone

5 Configuration reference

5.1 Configuration file syntax

The main configuration file uses a syntax very similar to the Javascript Object Notation (JSON) with few extensions.

Supported types:
- - Numbers (64 bit floating point). Notation: 13.4
- - Complex numbers. Notation: 1.2+3*I
- - Strings. Notation: "string"
- - Booleans. Notation: true or false.
- - Objects. Notation: { field1: value1, field2: value2, .... }
- - Arrays. Notation: [ value1, value2, .... ]
The basic operations +, -, * and / are supported with numbers and complex numbers. + also concatenates strings. The operators !, ||, &&, ==, !=, <, <=, >=, > are supported too.
The numbers 0 and 1 are accepted as synonyms for the boolean values false and true.
{} at top level are optional.
" for property names are optional, unless the name starts with a number.
Properties can be duplicated.
If properties are duplicated, they will be merged following JSON merge rules with overriding occuring in reading direction (last overrides previous).
Ex:
```
{
    value: "foo",
    value: "bar",
    sub: {
        value: "foo"
    },
    sub: {
        value: "bar"
    }
}
```
Will be equivalent to:
```
{
    value: "bar",
    sub: {
        value: "bar"
    }
}
```
Files can be included using include keyword (must not be quoted) followed by a string (without :) representing the file to include (path is relative to current file) and terminating by a comma.
Arrays can’t be included.
Merge will be done as for duplicate properties.
If file1.cfg is:
```
    value: "foo",
    include "file2.cfg",
    foo: "foo"
```
And file2.cfg is:
```
    value: "bar",
    foo: "bar"
```
Final config will be:
```
{
    value: "bar",
    foo: "foo"
}
```
A C like preprocessor is supported. The following preprocessor commands are available:

#define var expr

Define a new variable with value expr. expr must be a valid JSON expression. Note that unlike the standard C preprocessor, expr is evaluated by the preprocessor.

#undef var

Undefine the variable var.

#include expr

Include the file whose filename is the evaluation of the string expression expr.

#if expr

Consider the following text if expr is true.

#else

Alternative of #if block.

#elif

Composition of #else and #if.

#endif

End of #if block.

#ifdef var

Shortcut for #if defined(var)

#ifndef var

Shortcut for #if !defined(var)

In the JSON source, every occurrence of a defined preprocessor variable is replaced by its value.
Backquote strings: JSON expression can be inserted in backquote delimited strings with the ${expr} syntax. Example: `abc${1+2}d` is evaluated as the string "abc3d". Preprocessor variables can be used inside the expression. Backquote strings may span several lines.

5.1.1 JSON merge rules

Merge overriding direction depends on context, i.e source may override destination or the opposite.
JSON merge is recursive for Objects and Arrays.

Example, merging

{
    foo: { value: "bar" },
    same: "one",
    one: 1
}

with

{
    foo: { value: "none", second: true },
    same: "two",
    two: 1
}

Will become:

{
    foo: { value: "bar", second: true },
    same: "one",
    one: 1
    two: 1
}

assuming first object overrides second one.

In case of Array merging, the final array length will be the maximum length of all merged arrays.
For each element of the final array, merge will be done considering defined elements only.
Ex:

{
    array: [0, 1, 2, { foo: "bar" } ],
    array: [3, 4],
    array: [5, 6, 7, { bar: "foo" }, 8 ]
}

Will be merged to:

{
    array: [5, 6, 7, { foo: "bar", bar: "foo" }, 8 ],
}

5.2 Properties

log_filename

String. Set the log filename. If no leading /, it is relative to the configuration file path. See Log file format.

log_options

String. Set the logging options as a comma separated list of assignments.

layer.level=verbosity. For each layer, the log verbosity can be set to none, error, info or debug. In debug level, the content of the transmitted data is logged.
layer.max_size=n. When dumping data content, at most n bytes are shown in hexa. For ASN.1, NAS or Diameter content, show the full content of the message if n > 0.
layer.payload=[0|1]. Dump ASN.1, NAS, SGsAP or Diameter payload in hexadecimal.
layer.key=[0|1]. Dump security keys (NAS and RRC layers).
layer.crypto=[0|1]. Dump plain and ciphered data (NAS and PCDP layers).
layer.verbose=[0|1]. If layer is ipsec, dump all packets filtering informations.
time=[sec|short|full]. Display the time as seconds, time only or full date and time (default = time only).
time.us=[0|1]. Dump time with microseconds precision.
file=cut. Close current file log and open a new one.
file.rotate=now. Rename current log with timestamp and open new one.
file.rotate=size. Rename current log every time it reaches size bytes open new one. Size is an integer and can be followed by K, M or G.
file.path=path. When log rotation is enabled, move current log to this path instead of initial log path.
append=[0|1]. (default=0). If 0, truncate the log file when opening it. Otherwise, append to it.

Available layers are: ims, sip, media, rx, cx, n5

log_sync

Optional boolean (default = false). If true, logs will be synchronously dumped to file.
Warning, this may lead to performances decrease.

sip_addr

Array. Each item is an object representing a SIP server socket defined as follow:

addr: String. Set the IP address (and an optional port) on which IMS server will listen for SIP packets. The default port is 5060.
bind_addr: Optional string. Defines network interface on which IMS will listen.
If not specified, the addr parameter is used.
port_min: Optional integer (Default is 10000). Defines lower bound of UDP media socket.
port_max: Optional integer (Default is 20000). Defines upper bound of UDP media socket.

NB:

SIP socket object can be represented by a simple string. Thus, it will represent addr parameter and all other parameters will use default value.
For legacy, sip_addr can be a single SIP socket (Object or String) instead of an Array.

sctp_addr

String. Set the IP address (and an optional port) for MME connection.
This is only necessary for SMS over SG feature.

cx_server_addr

String. Set the IP address (and optional port) of Cx SCTP connection to the HSS. The default port is 3868.

cx_bind_addr

Optional string. IP address and optional port on which the Cx SCTP connection is bound. If not set, sctp_addr is used.

cx_origin_realm

Optional string. Defines the string sent in the Origin-Realm AVP for Cx messages. Default is set to amarisoft.com.

cx_origin_host

Optional string. Defines the string sent in the Origin-Host AVP for Cx messages. Default is set to ims.amarisoft.com.

cx_watchdog_duration

Optional integer (range 0 to 36000000, default = 0). Tw watchdog timer in milliseconds to send the Diameter Device Watchdog Request message. The value 0 deactives the watchdog.

rx_server_addr

Optional string. Set the IP address (and optional port) of Rx SCTP connection to the MME. The default port is 3868. If not set, cx_server_addr is used.

rx_bind_addr

Optional string. IP address and optional port on which the Rx SCTP connection is bound. If not set, cx_bind_addr is used.

rx_origin_realm

Optional string. Defines the string sent in the Origin-Realm AVP for Rx messages. Default is set to amarisoft.com.

rx_origin_host

Optional string. Defines the string sent in the Origin-Host AVP for Rx messages. Default is set to ims.amarisoft.com.

rx_watchdog_duration

Optional integer (range 0 to 36000000, default = 0). Tw watchdog timer in milliseconds to send the Diameter Device Watchdog Request message. The value 0 deactives the watchdog.

use_n5

Optional boolean (default = false). If set, the N5 interface is used instead of the Rx interface.

n5

Optional object used to configure the N5 interface with the PCF.

api_root: String. apiRoot as defined in 3GPP TS 29.501: <scheme>://<host>:<port>, where <scheme> is "http" or "https".
transaction_timeout: Optional integer (range 1 to 15000, default = 4000). Defines the timeout in milliseconds for a transaction with the PCF.
bind_addr: Optional string. IP address and optional port on which the N5 TCP connection is bound. If not set, cx_bind_addr is used.

domain

String. Global SIP domain used for IMPU and authentication. May be overriden at user level.
This parameter is not used to recover IMPU.

tcp_threshold

Optional integer (default = 1300). Set packet threshold in bytes to use TCP instead of UDP.

tcp_keepalive

Optional integer (default = 900). Time in seconds before sending keepalive on TCP connections. 0 means disabling keepalive.

tcp_keepcount

Optional integer (default = 2). Number of TCP keepalive failure before releasing socket.

session_expires

Optional object. Defines session timer configuration.
Parameters are the following:

duration: Optional integer (default = 1800). Session duration in seconds.
min: Optional interger (default = 90). Minimum allowed session expires.
refresher: Optional string (default = uac). Defines session refresher when it is up to the IMS to take this decision.
method: Optional string (default = update). Defines SIP method to use for session refresh when IMS is the refresher.
force: Optional boolean (default = true). If set to true, forces the refresher in IMS request with the refresher value.

For legacy purpose, session_expires can be an integer. If so, only duration is set and other parameters are kept to their default value.

100rel

Optional Boolean (default = true). Enable/disable 100rel support.

precondition

Optional string (default = on). Values can be "on", "off" or "silent".
On: IMS will handled QoS according to the standard.
Off: no precondition and no dedicated bearer establishment.
Silent: dedicated bearers will be established regardless the SIP and SDP content.
Note that a Rx connection is necessary to allow dedicated bearer establishment.

p_called_party_id

Optional boolean (default is false). Enable P-Called-Party-ID header for INVITE and MESSAGE requests.

ipsec

Optional boolean (default is true). Enable/disable support of ipsec.

ipsec_aalg_list

Array of strings. Each string represent IPsec authentication algorithm supported by IMS.
"null" may be used to indicate no authentication.
Supported algorithms are:

hmac-md5-96
hmac-md5-128
hmac-sha-1-96
hmac-sha-1-160
aes-cmac-96
aes-gmac

ipsec_ealg_list

Array of strings. Each string represent IPsec encryption algorithm supported by IMS.
"null" may be used to indicate no encryption.
Supported algorithms are:

aes-cbc
des-cbc
des-ede3-cbc
blowfish
aes-ctr
aes-gcm

ipsec_mtu

Optional integer (range 68 to 65535, default = 1400). MTU for IPsec network interface.

ipsec_ifname

Optional string. If set, use this interface for IPsec. In that case, ipsec_netns must be set and interface must be added to the network namepsace.
In this mode, used to run lteims with non root privileges, it is up to the user to configure the tun interface.
In particular:

Add tun interface to specififed network namespace
Add sip_addr IP addresses to the interface
Set MTU (ipsec_mtu will be ignored)
Set routes
Set CAP_SYS_ADMIN and CAP_NET_RAW capabilities to PROG

Ex:

setcap cap_sys_admin,cap_net_raw=ep lteims
ip tuntap add mode tun <ifname>
ip link set dev <ifname> name <ifname> netns <netns>
ip netns exec $netns ip addr add 192.168.4.1/0 dev <ifname>
ip netns exec $netns ip addr add 192.168.0.103/0 dev <ifname>
ip netns exec $netns ip link set <ifname> up mtu 1400
ip netns exec $netns ip route add default dev <ifname>

ipsec_netns

Optional string. Must be set if ipsec_ifname is set. Defines network namespace name used for ipsec.

dialog_timeout

Optional integer (default = 30). Time in seconds of call session. Stop call if no activity has been detected during this time.

auth_on_register_only

Optional boolean (default = true). If true, don’t try to authenticate other request than register (unless expires is set to 0).

trunk

Optional object. If set, IMS will accept incoming calls from a SIP trunk and will forward unknown calls to SIP trunk (https://tech-academy.amarisoft.com/how_to_run_volte_call_using_a_sip_trunk.wiki).
SIP trunk must accept non authenticated requests. Parameters are the following:

addr: String. IP address of the SIP trunk.
name: String. SIP trunk account user name.
domain: Optional string (default = same as addr). If set, use this for SIP uri domain.
tcp_threshold: Optional integer (default = 0). If > 0, will override global tcp_threshold parameter.

com_addr

Optional string. Address of the WebSocket server remote API. See Remote API.
If set, the WebSocket server for remote API will be enabled and bound to this address.
Default port is 9003.
Setting IP address to [::] will make remote API reachable through all network interfaces.

com_name

Optional string. Sets server name. IMS by default

com_ssl_certificate

Optional string. If set, forces SSL for WebSockets. Defines CA certificate filename.

com_ssl_key

Optional string. Mandatory if com_ssl_certificate is set. Defines CA private key filename.

com_ssl_peer_verify

Optional boolean (default is false). If true, server will check client certificate.

com_ssl_ca

Optional string. Set CA certificate. In case of peer verification with self signed certificate, you should use the client certificate.

com_log_lock

Optional boolean (default is false). If true, logs configuration can’t be changed via config_set remote API.

com_log_us

Optional boolean (default is false). If true, logs sent by log_get remote API response will have a timestamp_us parameters instead of timestamp

com_auth

Optional object. If set, remote API access will require authentication.
Authentication mechanism is describe in Remote API Startup section.

passfile: Optional string. Defines filename where password is stored (plaintext).
If not set, password must be set
password: Optional string. Defines password.
If not set, passfile must be set.
unsecure: Optional boolean (default false). If set, allow password to be sent plaintext.
NB: you should set it to true if you access it from a Web Browser (Ex: Amarisoft GUI) without SSL (https) as your Web Browser may prevent secure access to work.

com_log_count

Optional number (Default = 8192). Defines number of logs to keep in memory before dropping them.
Must be between 4096 and 2097152).

sim_events

Array of object. Each element gives an event configuration to execute for this UE.
Event configuration is exactly the same as for Remote API messages except that message field must be event.

sim_events_loop_count

If set, will define loop_count for each event of sim_events, See loop_count.

sim_events_loop_delay

If set, will define loop_delay for each event of sim_events, See loop_delay.

license_server

Configuration of the Amarisoft license server to use.
Object with following properties:

server_addr: String. IP address of the license server.
name: Optional string. Text to be displayed inside server monitor or remote API.
tag: Optional string. If set, server will only allow license with same tag.

Example:

license_server: {
    server_addr: "192.168.0.20",
    name: "My license"
}

sms_expires

Integer (default = 86400). Delay in seconds before SMS is removed from database. If a MO SMS contains the TP-Validity-Period field, it will be used instead of sms_expires.

sms_hook_only

Optional boolean (default = false). If set, when SMS is received and at least one WebSocket client has registered to sms event, don’t process SMS internally (Only CP/RP layer will be handled).

binding_expires

Integer (default = 3600, max = 864000). Default duration in seconds for registration.

subscribe_expires

Integer (default = 0, max = 864000). Subscription expiration. If set to 0, use value sent by UE.

user_agent

Optional string (default = Amarisoft-IMS-2024-12-13). SIP user agent.

force_user_agent

Boolean (default = true). If true, IMS user-agent will always be used, else remote peer’s one will be used.

path

Optional string (default = sip:ims.mnc001.mcc001.3gppnetwork.org). SIP path. If registration supports path, defines content of the Path header in registration response. If set to an empty string, Path header won’t be set.

timer_t1

Optional number (default = 2). SIP T1 timer duration in seconds.

timer_t2

Optional number (default = 16). SIP T2 timer duration in seconds.

timer_t4

Optional number (default = 17). SIP T4 timer duration in seconds.

custom_headers

Array of object. Each object represents a custom header to add to requests and/or responses, defined as follows:

name: Header name
value: Header value
codes: Number or array of numbers of the SIP responses on which to apply custom headers.
0 can be used for all codes.
methods: String or array of strings of the SIP method on which to apply custom headers.
* can be used for all methods.
If codes is set, the custom headers will be applied to the responses of the associated request.
replace: Optional boolean (default = false). If set, allow only one occurence of the header.

sms_centre_address

Optional object used to configure the SMS centre address. Contains the following parameters:

type_of_number: Optional enumeration "unknown", "international", "national" (default = "unknown"). SMS centre address type of number.
numbering_plan: Optional enumeration "unknown", "national", "private" (default = "unknown"). SMS centre address numbering plan identification.
number: String. Contains optional ’+’ at first position followed by a maximum of 20 digits. SMS centre address number.

sms_retry_delay

Integer. Time in s to retry SMS sending.

100rel

Optional boolean (default = true). Enable/disable support of provisional response

echo

IMPU (See impu). If set, this defines the phone number(s) for echo service.

mt_call_sdp_file

String. File to use as SDP when using MT call.

sms_message_filter

Optional object. Allows to define the IMS behavior for a list of SMS related messages.
Each property name represents a SMS message type. The ones currently supported are cp_data, cp_ack, rp_data and rp_ack.
Each property value is an enum: treat (message is processed), ignore (message is ignored) or reject (message is rejected).
By default all procedures are treated.

Example:

sms_message_filter: {
    cp_data: "treat",
    rp_ack: "reject"
}

sms_forced_cp_cause

Optional integer (range 0 to 255). Allows to override the CP error cause selected by the IMS with the one configured. Set to 0 to deactivate the override.

sms_forced_rp_cause

Optional integer (range 0 to 255). Allows to override the RP error cause selected by the IMS with the one configured. Set to 0 to deactivate the override.

mms_server_bind_addr

Defines network interface on which MMS server will listen. It is used to configure the MMSC in the UE. MMS proxy is not supported and shall not be configured in the UE.

Example:

mms_server_bind_addr: "192.168.3.1:1111"
MMSC: http://192.168.3.1:1111

mms_expires

Optional integer (default = 86400). Delay in seconds before MMS is removed from database.

5.2.1 User database options

ue_db

Array of objects. Configure the user database. Each element is an entry for one user. Note that this part can be shared between Amarisoft MME and IMS. The following properties are available:

imsi

Optional string. Set the IMSI.
Shall be present if nai is absent.

nai

Optional string. Network specific identifier-based SUPI.
Shall be present if imsi is absent.

multi_sim

Optional boolean (default = false). If true, allow several UEs to have the same IMSI (useful when using several identifical test SIM cards in different UEs at the same time). They are distinguished with their IMEI. Note: it is only allowed with the XOR authentication algorithm.

impi

String. Defines user IMPI. Must be fully filled with hostname if necessary.
If you don’t know your IMPI, please look at IMS logs inside REGISTER request. The IMPI must match the username argument inside Authorization header.

impu

Array of strings or array of objects.
Each string represent an IMPU and can be a sip URI or a telephone number.
Note that sip URI must not include hostname.
If IMPU does not start by a scheme, it is assumed to be a sip URI.
Ex:

sip:user
user
tel:+33123456789

If impu is an object, it has following members:

impu

IMPU as defined above.

imei

IMEI associated to this IMPU. Allows to filter calls and SMS for a specific UE.
Only relevant if multi_sim is set to true.

anonymous

Optional boolean (default is false). If true, allow Anonymous connection (Emergency call) and mask impu in SIP headers.

anonymous_callback

Optional number (default is 0). If anonymous is set, defines how long in seconds after an anonymous call has been done, the network can call back the caller. In that case, caller will be identified with an sip IMPU derived from its IMEI.

authentication

Optional boolean (default is true). If false, disable authentication.

ring_only

Optional boolean (default is false). If true, IMS will go up to ringing state but not further.

precondition

Optional string. Values can be "on", "off" or "silent".
On mode: IMS will try to guess precondition from supported header, SDP content and/or VoLTE compatibility of client.
Off mode: no precondition and no dedicated bearer establishment.
Silent mode: dedicated bearers will be established whatever the SIP and SDP content.

100rel

Optional boolean (default = true). Enable/disable 100rel support for this IMPU.

preferred

Optional boolean (default: false). If set, this impu will be used for preferred identity and for INVITE request URI.

asserted

Optional boolean (default: false). If set, this impu will be used for asserted identity.

associated

Optional boolean (default: true). If set to false, this impu will not be used for associated URI.

display_name

Optional string. If set, SIP headers will use this field for display name.

domain

Optional string. Used to override user or global config.

p_called_party_id

Optional string. If set, forces P-Called-Party-ID header for INVITE and MESSAGE requests, no matter if p_called_party_id global parameter is set or not.

answer_delay

Optional number. If set, when doing a echo call on this IMPU, OK response to INVITE request will be delayed by answer_delay in seconds.

sms_delay

Optional number. If set, IMS will wait sms_delay seconds before sending SMS to this IMPU.

media_delay

Optional number. Delay sending of media packet in seconds.

remote_control

Optional boolean. If set to true on a echo impu, the sending of final of INVITE request will be controled by dialog_set remote API with answer action (The delay to send answer is defined by dialog_timeout parameter.
A remote API invite event will be sent with dialog session_id.

sdp_file

Optional string. When used in echo mode, use the SDP file to force the media sent in server SDP response.

session_expires

Optional object. If set, will override global session timer parameters for that impu, See session_expires.
If IMS is the server (MO call and echo call), caller configuration will be used, else (MT call) callee’s one will be used.

bitrate_factor

Optional number (Default = 1). Media bitrate are estimated from SDP. When setting up the dedicated bearer via Rx interface, the bitrate is multiplied by this number.

video

Optional boolean (default = true). If set to false, video media will be rejected.

callflow_modifier

Optional object or array of objects. This allows to modify IMS behavior and messages.
Each object will define a modification in the SIP callflow.
The modifier will be applied with following rules:

On MO dialogs, callee modifiers will be used.
On MT dialogs, caller modifiers will be used.

Each object is defined this way:

method

Optional string. Defines on which step to apply modifier (if not set, applies on any of the following). Modifier applies on reception or sending of message depending on dir parameter
If set to INVITE.OK, modifier applies on final answer of INVITE request.
If set to INVITE.TRYING, modifier applies on 100 SIP responses.
If set to INVITE.RINGING, modifier applies on 180 SIP responses.
If set to INVITE.SESSION_PROGRESS, modifier applies on 183 SIP responses.
If set to INVITE, SUBSCRIBE, REGISTER, UPDATE, CANCEL, PRACK, MESSAGE, modifier applies on received or sent requests.
If set to REGISTER.SOS, modifier applies on reception of emergency REGISTER.
If set to REINVITE, modifier applies on received or sent INVITE requests during an established dialog.

code

Optional number (between 100 and 699). If set, modifier will generate a SIP response with this code and modifier will apply on this message.
If code is not set, no response wil be generated.

stop

Optional boolean (default = true). If set to true and modifier applies within a dialog, dialog will be stopped. In that case, normal callflow will be stopped.

dir

Optional string (default = both). Can be tx to apply modifier on sent messages, rx to apply modifier on received messages or both for both type of messages.

transparent

Optional boolean (default = false). If true, modifier will be applied without stopping the normal call flow.

content

Optional string. Response body will be filled with content file on generated message. If set to null, any already set content with same content_type will be removed (Ex: use application/sdp to remove SDP).

content_type

Optional string. Mandatory if content is set, will define response content type.

access_network

Optional string (default = false). List of RAT separated by comma. If set the callflow will only be affected if P-Access-Network-Info matches the selected RAT. Can be lte (3GPP-E-UTRA), nr (3GPP-NR), or n3gpp (IEEE).

custom_headers

Optional Array of object. Apply specific headers on the generated response as defined in custom_headers, except that code and methods parameters are useless.

impu

Optional string. Is set, modifier will be applied only if counterpart of the dialog matches this IMPU:

On MO dialogs, caller IMPU.
On MT dialogs, callee IMPU.

imei

Optional string. Is set, modifier will be applied only if counterpart (Cf impu) has same IMEI provided during registration.

ttl

Optional integer (> 0) (Time To Live). If set, callflow modifier will be removed after having being applied ttl times.

tts

Optional integer (default = 0) (Time To Start). If set, callflow modifier will not be applied for the the tts times it has been triggered. This will differ ttl decreasing.

send_delay

Optional number (default = 0, max = 60). Delay in seconds of SIP message sending

code