The topic of codec selection comes up regularly in the VoIP provider world. Specifically,
concerns regarding customers that have ‘hard coded’ their codec to
G729 to the point they won’t allow G711. This explains how
codecs get assigned to call legs in Cisco IOS.
You can set up a codec
class as described below.
voice
class codec 100
codec
preference 1 g729r8
codec
preference 2 g711ulaw
That works just as you
would expect: G729 is the top preference, if that’s not available
revert to G711.
Now, you apply that to
a voip dial peer:
dial-peer
voice 150 voip
destination-pattern
.T
session
protocol sipv2
session
target ipv4:1.1.1.1
voice-class
codec 100
I personally have
another dial-peer set up for outbound fax. For that, I “hard code”
to G711, like this:
dial-peer
voice 160 voip
destination-pattern
*.T
translation-profile
outgoing fax
session
protocol sipv2
session
target ipv4:1.1.1.1
codec
g711ulaw
Interestingly enough –
if you specify no codec for a dial-peer – IT WILL DEFAULT TO
G729 AND NOT ALLOW G711. Net, you get the hard-coded G729
scenario if you do nothing to your dial peer.
Copyright ©1993-2024 Joey E Whelan, All rights reserved.
