We replaced a 2811 gateway with a new 4331 ISR router and voice quality is terrible. Information -
Code - isr4300-universalk9.03.14.00.S.155-1.S-std.SPA.bin
Voice Interfaces - Both T1 PRI and POTS line via FxO
CallManager Version 10.5, latest patch
Gateway Protocol - Issue occurs with both H323 and MGCP
Show Controller T1 shows no slips or errors for the PRI
Protocol - Both G.711 and G.729
The scenario is that voice quality on the IP Phone side of a call hears hissing and noise throughout the call but especially when the IP Phone side is speaking. The hissing and noise can be heard as the call is being processed in the gateway. Real weird. We used a real blanket config (h323) and got these results. Anyone else experiencing this? Suggestions?
Might be worth checking if VAD is in use during a call, VAD generates background noise (comfort-noise or hiss) to fill silent gaps during calls.
TCC_2 posted "How to confirm that VAD is enabled and how to disable it on Cisco IOS gateways" this some years ago..
To confirm whether Voice Activity Detection (VAD) is enabled on a call-by-call basis, perform these steps:
To disable VAD, perform these steps:
I wouldn't say our issue is so much a hissing, more like garbled voice when one party is talking. Its incomprehensible what they are saying. However it seems to match the other changes we made, going from 28xx router to 4331 with the new FXO card.
We are currently running:
boot system flash:isr4300-universalk9.03.13.05.S.154-3.S5-ext.SPA.bin
Cisco IOS XE Software, Version 03.13.04.S - Extended Support Release
Cisco IOS Software, ISR Software (X86_64_LINUX_IOSD-UNIVERSALK9-M), Version 15.4(3)S4, RELEASE SOFTWARE (fc3)
I'll try a new IOS and report back. On a side note, what are all the additional files when I do 'show flash:'? Are they necessary files for the newer XE OS?
I have the same problem, even using "no vad" command.
What I know is that some old Cisco phones like 7940, doesn't support G722 codec.
If this codec is forced on your CCM, you have to apply on your router a profile to forcé other codecs supported by old phones:
voice class codec 100
codec preference 1 g729r8
codec preference 2 g711alaw
codec preference 3 g711ulaw
dial-peer voice 1004 voip
incoming called-number .
voice-class codec 100
dial-peer voice 1000 voip
session target ipv4:XXX.XXX.XXX.XXX
voice-class codec 100
voice-class h323 1
I'm sure "mzajeski" is most correct here (+5)
You may likely be hitting this bug;
Hissing noise can be heard prominently on .sout. The hissing noise is consistent while the called party is not yet answering then it comes in and out on the entire conversation. It can be heard most of the time when calling party is not talking. "No vad" and "no comfort noise" are configured on the voice port and VOIP dial-peer. This was experienced by the customer on his environment and was replicated at Cisco lab. There is a POTS line connected to NIM-4FXO on a 4331. DSP type, DM8147 and SP2700.
cisco ISR4331/K9 (1RU) processor with 7831854K/6147K bytes of memory.
System image file is "bootflash:isr4300-universalk9.03.13.01.S.154-3.S1-ext.SPA.bin"
Voice Card -
"NIM-4FXO Voice Analog Module"
DM8147 DSPWare 37.3.4
use hidden command"non-linear mute" under voice-port configuration.