[asterisk-users] *SOLVED* SIP trunk gives fuzzy / distorted audio on mobiles, OK on fixed lines

A J Stiles asterisk_list at earthshod.co.uk
Thu Jul 31 10:48:42 CDT 2014

I have now fixed this issue, and am posting this for the benefit of anyone else 
who may be suffering with a similar problem.

It was, as I suspected all along, a subtle misconfiguration at this end.

The fix was to give the SIP trunk its own configuration stanza in sip.conf as 


and replace all instances of


In the absence of that important little stanza, the [general] settings were 
applying to the ad-hoc SIP endpoint; meaning that even in spite of explicitly 
setting the outbound SIP codec, Asterisk was insisting to use G726.

No sooner had I worked this out, than the SIP trunk provider e-mailed 
basically to confirm my thinking.

The moral of this story:  Never trust a configuration file written by someone 
else, no matter how close it was to working  ;)


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