[Asterisk-Users] Choppy Ringing

[Eric Wieling aka ManxPower]

Todd Weiser wrote:

> We recently changed our asterisk system to begin using G.729a as the
> primary codec.  We have a Cisco 1700-series router which connects to the
> PSTN via FXO ports, along with Cisco 7940 SIP phones.  Everything is
> working great, except...  When an inbound caller calls into our system,
> they hear an IVR.  When the caller dials an ext (SIP phone), the ringing
> progress tone is choppy/distorted...  However, the voice call itself
> sounds fine.  Asterisk, the Cisco phone, and the call gateway are all
> configured to use rfc2833.  From my research, asterisk generates
> progress tones out-of-band (I think) unless turned on.  We don't have
> any problems with the progress tones when G.711u is used.  Any
> help/ideas would be greatly appreciated.

Once the call has been answered (IVR, etc), then Asterisk will have to 
send the ringing sound inband.  G729 distorts tones like DTMF and ringback.