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

James Thomas jthomasdpu at gmail.com
Thu Jul 31 10:03:56 CDT 2014

Is the quality the same incoming from mobile as outgoing to mobile?

On Wed, Jul 30, 2014 at 4:51 AM, A J Stiles <asterisk_list at earthshod.co.uk>

> I'm having a problem with a new SIP trunk.
> Calls within the UK to fixed lines are fine, but calls to mobiles have
> noticeably poorer audio quality.
> I thought it might have been a codec issue; we have used G.726 for internal
> and external calls  (over primary ISDN and GSM).  So I tried allowing
> "alaw",
> (G.711 A-law)  which is the native codec used within the PSTN in this
> country,
> but this made no improvement.
> We had
>   disallow=all
>   allow=g726
> in the [general] section of sip.conf.  In the section for one of the
> phones, I
> added
>   allow=alaw
> and then inserted
>   Set(SIP_CODEC=alaw)
> in the relevant part of extensions.conf.  For good measure, I also added
>   NoOp(Codec was ${SIP_CODEC})
> in the "h" extension.  The messages in the Asterisk CLI appeared to show
> that
> the audio codec was correctly being set to "alaw", and on hangup I got
> "Codec
> was alaw", but there was no improvement to the sound quality.
> Is there something I am doing wrong, or do I need to get in touch with our
> trunk provider?
> --
> Note:  Originating address only accepts e-mail from list!  If replying off-
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