[maemo-users] N900 power consumption - particularly on SIP VoIP

From: Joerg Reisenweber joerg at openmoko.org
Date: Thu Apr 22 18:15:04 EEST 2010
[Henrik Frisk Mi  21. April 2010]:
> But to my surprise, the
> biggest power hog was the sip account. When I disabled it my up-time
> was more reasonable. Anyone knows a way to reduce the power
> consumption without disabling the account? Some of the advanced
> options I don't really know what they do.
>  It's really a shame because I was so pleased to finally have found a
> mobile sip client that really works. Any suggestions are appreciated.

Hi Henrik,

as usual the main battery energy leak in *idle* is 3G TX (and to a lower 
degree 2(.5)G as well). TX occurs for each bit of data sent upstream to the 
internet including TCP ACK for downstream TCP data. 

So a SIP user agent *may* idle completely for hours, just waiting for an 
inbound call. But usually you see TX activity caused by re-registrations, NAT 
keep-alive pkgs, MWI notification, propagation of own online status, updating 
online status of contacts(!), STUN, hosted NAT traversal, and even arbitrary 
bogus data packages inbound to port 5060 or the RTP ports.
Alas there's relatively little you can do about this, as most of the issues 
depend on your SIP registrar's and your GSM/UMTS provider's config of their 

You could install SIP Swiss army knife User Agent twinkle [1] - probably to 
your PC as regrettably there's no N900 or even ARM version I'd know of - 
tether N900 to PC to use the 3G of your provider, and then try if you find 
some better settings for the 512 knobs and dials you can tweak SIP with. 
Things like changing port from 5060 to a value not associated to SIP come to 
mind, as it's even possible your carrier isn't interested that much in a 
working SIP over his network. If you're really going to dive into that, feel 
free to ping me on IRC [2], I might still be able to walk you through 
twinkle's various functions and settings, and help create and interpret decent 
twinkle logs.

FWIW: My SIP account at sipgate.de seems to work relatively flawless, though I 
never thoroughly tested the maximum battery endurance when connected strictly 
via 3G only.


[1] http://www.twinklephone.com
[2] freenode #maemo, nick: DocScrutinizer 
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