How asterisk use pri channel

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Asterisk Users 5 Comments


We have two pri line and I want to see how asterisk distribute
outgoing call per channels

I meant it use first last channel 47 or it will use first channel?

Or it will allocate dynamically ?

5 thoughts on - How asterisk use pri channel

  • Awesome!!

    Do you know if i want to use only specific channel for call out then how do i write dialplan ? I want to use channel 25 specific for my extension


  • I hope my understanding is not wrong!

    (1) DAHDI/i2/25/XXXXXXXXXXX, is not a valid format for Dial. Rather it
    should be DAHDI/i2/XXXXXXXXXXX and it would use a channel from span 2
    (/etc/dahdi/system.conf) for outgoing call.

    (2) To dial from channel 25 , use DAHDI/25/XXXXXXXXXXX


  • I appriciate your reply,

    But believe me no one option works for me. I tried dahdi/25/XXXXXXX
    but it still using pri first channel or anyother channel

    In old zap school you can do that but in dahdi I don’t think you can.
    Until unless you create g1 g2 … Group in chan_dahdi.cfg and map
    channels there.

  • Dialing DAHDI/25/xxxxxxxx will dial channel 25 only.
    For ISDN spans I do not recommend doing that because your call will
    fail if that channel is already in use when there may be other B channels
    available for the call.

    You should be creating groups for your ISDN spans.


  • It should be in some dial help but it is not. The syntax is
    channel driver specific and every channel driver has its own needs.
    I created that comment block in chan_dahdi.c since I could not find
    it elsewhere when studying the code.