Conf bridge audio doesn't work with 500+ devices but does with 200 devices


I am trying to send an audio message to sip devices for a PA system. I am using chan_sip in Asterisk 18, utilizing confbridge to bring 508 SIP devices into a conference (muted on the device end) and we don’t get any audio. However, if we use a smaller number of devices like 200 we get audio. Also I do not have max_members set for a confbridge so it should have no limit. Any ideas of what might be happening?

Thank you.

  1. See ConfBridge - Asterisk Project - Asterisk Project Wiki “Maximizing
    Performance” in case you’re not doing all those things already.

  2. Try finding the maximum number of endpoints your machine can support (a)
    with any sort of audio at all, and (b) with good quality audio. I believe
    anything higher than this number will require a higher spec server running

Since you say 200 devices work (presumably perfectly satisfactorily without
distortion) and 500 devices don’t, try 350. If they work, go up to 425; if
they don’t, cut down to 275. Keep on halving the number of devices you add
(if the conference works) or remove (if it doesn’t) and you’ll quickly find the
number which your system supports.


Although there may not be hard limits in the code, I can’t imagine that it was expected that people would use it for huge conferences. Limits will depend on a lot of factors, including CPU capacity, network capacity and the choice of codecs.

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