[asterisk-users] Question about Warning message

Matthew Jordan mjordan at digium.com
Mon Feb 23 12:16:59 CST 2015

On Mon, Feb 23, 2015 at 11:27 AM, Fabian Borot <fborot at hotmail.com> wrote:

>                     Starting with Asterisk 13.1 we are seeing this WARNING
> messages a lot in our logs and console:
> WARNING[25164][C-0004865e]: chan_sip.c:7364 sip_write: Can't send 10 type
> frames with SIP write)
> We found that line in function "sip_write" inside "chan_sip.c".
That would be a CNG frame (AST_FRAME_CNG). While a frame exists to convey
CNG to capable channel drivers, CNG itself is not implemented or handled in
chan_sip (or most of Asterisk).

> In our previous version (11.2.1) we did not see those messages being
> printed (same verbosity level). We compared both versions of the functions
> and see no difference at all in the 'default' switch case that handles
> that. We think/assume that that function is being called in
> different places on each version (11.2-1 vs 13-1).

There's a lot of intervening points between sip_write and whatever
generated the CNG frame. Most likely, res_rtp_asterisk is generating this
due to receiving a CN RTP packet. On the receiving channel, that will
normally just generate a single NOTICE message for that RTP session and be
done. It's possible that in your Asterisk 11 deployment, your channels were
natively bridged, which would result in the RTP packet containing the CN
indication being directly written out to the bridged party. Depending on
the configuration you are using in your Asterisk 13 deployment, your
channels may no longer be natively bridged, at which point the CNG frame is
created and passed up to the core. If that is the case, then I would expect
to see that WARNING message in either version of Asterisk.

> We also think it has to do with the asterisk receiving rtp packets with
> comfort noise which is not supported by asterisk.


> We would like to know what can we do about it to behave more like the
> version 11?
Check how the channels are bridged. If they are natively bridged in 11 but
not in 13, and native bridging is an option, you may want to determine why
the channels are not natively bridging in 13.

> We are not sure but could it be that version 11 handles it better ?. I am
> attaching the functions on both versions for your review.
Not at all. CN handling was not changed between 11/13.


Matthew Jordan
Digium, Inc. | Engineering Manager
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at: http://digium.com & http://asterisk.org
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