Gizmo and Fritz!Box Fon

This is a little esoteric even by Little Storping standards, but partly in recognition that someone else maybe using the above combination of VOIP service and hardware, and mostly so I don’t forget what I just did, I’m going to describe the configuration changes I made to the Fritz!Box to try to improve call quality.

Gizmo generally has good call quality from Mac to Mac or Mac to POTS, but I’ve been dissatisfied when calling from my phone through the ATA router. It’s a Fritz!Box Fon with the British (Annex A) firmware 06.04.24 . Happily it runs an embedded Linux accessible via Telnet which is turned on by dialing #96*7* (and off again by dialing #96*8*). Once in, turn on verbose mode using voipd -s (to stop it) and then voipd -v (for verbose).

When calling I observed:

ar 4 23:10:05 voipd[776]: allowed bandwidth 432000 for sip:xxxxxxxxxxxxxx@proxy01.sipphone.com

Mar 4 23:10:05 voipd[776]: xxxxxxxxxxx@proxy01.sipphone.com: bandwidth left 432000

Mar 4 23:10:05 voipd[776]: audio: 18 (18 G729/8000)

Mar 4 23:10:05 voipd[776]: audio: 18 (18 G729/8000) => (18 (18 G729/8000))

Mar 4 23:10:05 voipd[776]: audio: 97 (97 iLBC/8000)

Mar 4 23:10:05 voipd[776]: audio: 97 (97 iLBC/8000) => (97 (97 iLBC/8000))

Mar 4 23:10:05 voipd[776]: audio: 0 (0 PCMU/8000)

Mar 4 23:10:05 voipd[776]: audio: 0 (0 PCMU/8000) => (0 (0 PCMU/8000))

Mar 4 23:10:05 voipd[776]: audio: 8 (8 PCMA/8000)

Mar 4 23:10:05 voipd[776]: audio: 8 (8 PCMA/8000) => (8 (8 PCMA/8000))

Mar 4 23:10:05 voipd[776]: audio: 101 (101 telephone-event/8000)

Mar 4 23:10:05 voipd[776]: audio: 101 (101 telephone-event/8000) => (101 (101 telephone-event/8000))

Mar 4 23:10:05 voipd[776]: 130.94.88.90 15530 – 7078 audio 18(G729)

Mar 4 23:10:05 voipd[776]: Codec G729 (18) – audio 42400 hold=none (none) (by local)

I don’t know why it’s choosing G729, I already have always use voice coding in fixed-line network quality on the advanced setup page through the web interface. Oh well, the answer’s here.

nvi /var/flash/voip.cfg

The interesting lines are:

use_audiocodecs = no;

audiocodecs = “PCMA”, “PCMU”, “G726-32”;

Changing the no to a yes makes the fritz box use the codecs in a preference order shown in the second line.

Now I make a call and:

Mar 4 23:21:20 voipd[800]: allowed bandwidth 432000 for sip:xxxxxxxxxxxxxx@proxy01.sipphone.com

Mar 4 23:21:20 voipd[800]: xxxxxxxxxxx@proxy01.sipphone.com: bandwidth left 432000

Mar 4 23:21:20 voipd[800]: audio: 0 (0 PCMU/8000)

Mar 4 23:21:20 voipd[800]: audio: 0 (0 PCMU/8000) => (0 (0 PCMU/8000))

Mar 4 23:21:20 voipd[800]: audio: 8 (8 PCMA/8000)

Mar 4 23:21:20 voipd[800]: audio: 8 (8 PCMA/8000) => (8 (8 PCMA/8000))

Mar 4 23:21:20 voipd[800]: audio: 101 (101 telephone-event/8000)

Mar 4 23:21:20 voipd[800]: audio: 101 (101 telephone-event/8000) => (101 (101 telephone-event/8000))

Mar 4 23:21:20 voipd[800]: 198.65.166.147 18090 – 7078 audio 0(PCMU)

Mar 4 23:21:20 voipd[800]: Codec PCMU (0) – audio 106000 hold=none (none) (by local)

I’ll be keeping an eye on it, but it does look like it’s worked.

Don’t forget to turn telnet off (#96*8*)!

About Simon Wood

E-learning officer, lapsed mathematician, Doctor Who fan and garden railway builder. See simonwood.info for more…

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