IAX

IAX channel

This module supports the IAX protocol by using the Yiax library.

From a routing module you can call an IAX channel like this:

extension=iax/iax:user@ip:port/called_number

For example, in regexroute.conf you can have:

^2$=iax/diana@10.0.0.1/123

if you want to use the default protocol port (4569), or

^2$=iax/diana@10.0.0.1:4569/123

if you know that the called party is using the given port for incoming connections.

Trunking

IAX trunking means that audio data between 2 peers (same ip/port) can be combined into a single packet for multiple calls. E.g. an entity wanting to send trunked media packets from local ip 1.2.3.4:4569 to 1.2.3.5:4569 would gather media packets from multiple calls into a single packet and send it when a certain amount of time had ellapsed or the packet had reached some length limit. It is essential to understand that trunking can occur between same local/remote ip/port: packets for calls with different local or remote ip/port can't be put together in a trunked packet. The advantage of using trunking is to lower the bandwidth: the number of sent packets decreases leading to lower IP overhead.

In the next images the green, blue and red rectangles represents audio packets sent by different IAX calls. The images show how audio packets are sent without trunking and with trunking. Attach:iax_trunk.png

NOTE: The order of audio packets inside a trunked packet is not important.

Extra documentation can be found here:

• http://tools.ietf.org/html/rfc5456#section-7.1
• http://www.voip-info.org/wiki/view/Asterisk+bandwidth+iax2
• http://www.voip-info.org/wiki/view/IAX

For all calls the remote party can send trunked audio frames.
They will be handled automatically, there is no configuration for it.

To send trunked frames each call must be configured explicitly:

* Outgoing calls:

The 'call.execute' message must have a trunkout=true parameter

^2$=iax/diana@10.0.0.1:4569/123;trunkout=true

• Incoming calls

A trunkin=true parameter must be set when routing or executing an incoming IAX call:

[contexts]
${module}iax=if ${ip_host}^10\.0\.0\.1=;trunkin=true 

or

[default]
^3$=sip/sip:1234@1.2.3.4;trunkin=true

Notes:

• • The port you set it's the port the library is using to listen for incoming connections. If you change the default protocol port the callers might not know the new one, so any call they made will fail.
  • When you set a route, be sure you know the destination's port. Again, if the port is incorrect the call will fail.
  • If you set the preferred format to a non existing or not enabled one another format will be chosen for library use.

Configuration

File yiaxchan.conf:

yiaxchan.conf

[general]

This section sets global variables of the implementation

port

int: UDP port for incoming connections

port=4569

addr

ipaddress: IP address to bind to

addr=0.0.0.0

force_bind

boolean: Try to use a random port if failed to bind on configured one

Defaults to yes

force_bind=yes

calltoken_in

boolean: Use call token ip address authentication on incoming calls

Note

If the caller don't support the call token IAX extension the call request

will be ignored anyway

This parameter is applied on reload

Defaults to no

calltoken_in=no

calltoken_out

boolean: Offer call token ip address authentication on outgoing calls

This parameter is applied on reload and can be overridden from routing

Defaults to yes

calltoken_out=yes

calltoken_rejectmissing

boolean: Reject incoming calls without call token support

when calltoken_in is enabled

If disabled the requests will be ignored (dropped)

This parameter is applied on reload

Defaults to yes

calltoken_rejectmissing=yes

tos

keyword: Type Of Service to set in outgoing UDP packets

numeric TOS value or

lowdelay, throughput, reliability, mincost

tos=0

read_threads

int: Number of threads that read packets from socket

read_threads=1 in client mode, 3 in server mode

event_threads

int: Number of threads that process events

event_threads=1 in client mode, 3 in server mode

trunk_threads

int: Number of threads that service trunked voice packets

trunk_threads=1

thread

keyword: Default priority of the data service threads (socket listener and data trunking)

Can be one of

lowest, low, normal, high, highest

It is a bad idea to set a low priority for anything but testing

thread=normal

printmsg

boolean: Print sent/received frames to output if the module's debug

level is at least 9

This parameter is applied on reload

Defaults to yes

printmsg=yes

[formats]

This section allows to individually enable or disable the codecs

default

bool: Default enabling state for codecs

default=enable

preferred

string: Preferred format to use

preferred=

slin

bool: Uncompressed 16-bit signed linear

slin=enable

mulaw

bool: Companded-only G711 mu-law

mulaw=enable

alaw

bool: Companded-only G711 a-law

alaw=enable

gsm

bool: European GSM 06.10

gsm=enable

lpc10

bool: LPC 10

lpc10=enable

=]