I spent some time with my parents about a month ago fine tuning the echo cancellation on our SIP phones. Today I got a chance to refresh my memory while connecting the phones of a friend to a CallWeaver PBX I had setup for him. Hopefully I have now collected in one place all the settings that were changed from the factory defaults. If you have a Linksys SPA3102 phone adapter or a Linksys SPA942 phone, you may find some useful hints in here.
First navigate to the advanced voice administration pages on your device:
- Linksys SPA3102 / SPA2102: Admin Login > Advanced > Voice
- Linksys SPA942: Admin Login > Advanced
The following settings work well for me:
| Tab | Section | Setting | Value | Remarks |
|---|---|---|---|---|
| SIP | RTP Parameters | RTP Packet Size | 0.020 | |
| Regional | Miscellaneous | Time Zone | GMT +02:00 | Finland |
| Daylight Saving Time Rule | start=3/-1/7/3;end=10/-1/7/4;save=1 (European Union) |
|||
| Regional (SPA3102) (SPA2102) |
Ring and Call Waiting Tone Spec | Ring Waveform | Sinusoid | Finland |
| Control Timer Values | Hook Flash Timer Min | .05 | ||
| Miscellaneous | More Echo Suppression | yes | ||
| Miscellaneous (Siemens Gigaset 3000) |
FXS Port Input Gain | 16 | ||
| FXS Port Output Gain | -15 | |||
| Caller ID Method | Bellcore (N.Amer, China) | |||
| Caller ID FSK Standard | bell 202 | |||
| Miscellaneous (Siemens Gigaset E450) |
FXS Port Input Gain | 0 | ||
| FXS Port Output Gain | -3 | |||
| Caller ID Method | DTMF (Finland, Sweden) | |||
| Phone (SPA942) |
Audio Input Gain (dB) | Handset Input Gain | 6 | |
| Headset Input Gain | 0 | Hello Direct Unaural | ||
| Acoustic Echo Canceller Enable | yes | |||
| Ext 1-4 (SPA942) Line 1-2 (SPA3102) (SPA2102) |
Network Settings | Network Jitter Level | low | Echo suppression |
| Jitter Buffer Adjustment | up and down | Echo suppression | ||
| Proxy and Registration | Register Expires | 120 | Notice network problems faster | |
| User (SPA942) |
Supplementary Services | Date Format | day/month | |
| Audio Volume | Back Light Timer | 30 s | Maximum timeout | |
Hi,
I’ve been looking at buying some Linksys SPA942 phones. Would you recommend them?
Bert
Bert Balliss — 11.1.08 @ 19:06
Hi Bert,
The SPA942 does everything I need from a phone. I like the multiple line keys so it is easy to see from afar which line is ringing. The backlight is essential for clear reading of the display (and this is why I chose SPA942 over the SPA941). The built-in headset jack is also one of my favorite features, and it has a dedicated key on the phone set. Message waiting indication (MWI) works perfectly and includes per-line indication.
I have not setup call transfers or conference calls through Asterisk yet, as these features have worked fine for me as implemented on the SPA942. Eventually I want to use Asterisk for those, though.
The PA100 power supply (not included with the phone) is unfortunately wide, even if it is not the biggest power supply I’ve come across. I’ve just ordered more SPA942 phones, but I’ve bought other power supplies this time in a narrow form factor, better suited for those crowded power strips. Of course, if you have power-over-ethernet (802.3af) support on your network, you won’t have to worry.
From what I’ve read, shared (or bridged) line/call/extension appeareances are not implemented in a way compatible with Asterisk. Since I have a PBX background, I’m much happier with call parking anyway. However, if you are used to working with a key system, this might be an issue for you.
Kimmo Suominen — 12.1.08 @ 21:18
Thanks for the detailed reply.
Ah that’s worth knowing. It’s a pet hate of mine when power supplies overlap the neighbouring sockets too.
Bert Balliss — 14.1.08 @ 12:30
I thought I had good enough quality power supplies picked for the phones, but unfortunately that was not the case. The alternative power supply was causing a buzzing sound, which also threw echo cancellation out of whack. Back to the PA100…
Kimmo Suominen — 22.1.08 @ 15:33