How to enter IP address on phone menu? -- Solved
JohnLennon:
For VoIP quality of the line and latency are more important than throughput. Once you get just 256 KB/s (up/down) you can handle 2 simultaneous VoIP calls at a good quality with bandwidth for data too. I installed in this configuration 2 weeks ago, my in-laws have a business and decided to switch to VoIP without consulting me. After I upgraded their router to a more modern one (4 years old with QoS I had laying around vs the 8 yeard old they had) the quality improved without choppiness.
At first I thought the chances were slim with a naked DSL (dry loop) capped at 256Kb up/down, but the first set of tests for VoIP showed actually the quality was good.
I recommend this VoIP quality test http://myspeed.visualware.com/servers/namerica/iad.php?testtype=-1&codebase=mcsiad.visualware.com
In some cases a simple speed test insn't good: http://www.speakeasy.net/speedtest/ as it only measure bandwidth, not latency, packets lost, consistent stream of data, etc.
There is more but this would be a good start for your friend.
QBZappy:
JohnLennon,
Thanks
plugger2:
Quote from: QBZappy on March 23, 2011, 10:23:04 pm
I wonder what is the lowest bandwidth the OBi (SIP) can operate on and give acceptable call quality.
Depends on the codec being used. G729 and G729a are much more efficient with respect to bandwidth usage than G711a or G711u, for example. G729 also has the advantage of being more tolerant of jitter/lost packets etc. I generally use G729 or G729a as my default codec for VoIP.
MichiganTelephone:
I'll agree that G729 can be useful as a codec of last resort when you have seriously constrained bandwidth, but I disagree with plugger2 in that I would not used it unless there was no other way that would work. I personally think G729 has mediocre to horrible sound quality. I use only G711 and several users of our Asterisk server have commented on how clear the calls are. Unless you are running under serious bandwidth constraints, or you don't mind your calls having only bad cell phone quality, I'd personally avoid G729 like the plague. Not saying what anyone else should do, but that's how I feel about it.
In fact, I wish that the OBi's offered support for a wideband codec, in particular G722 as used in Asterisk (not g722.1 or g722.2, which are not supported by Asterisk). While some folks think that would be useless because phones aren't designed to handle anything above 4,000 Hz, I don't think that's necessarily true, otherwise a landline phone company would not have to give DSL customers a filter to put in their phone's connecting cable. The purpose of that is to filter out higher frequency tones (the DSL data stream) that would otherwise be heard, which are above 4000 Hz! So while a wideband codec might not offer the same improvement that it would on a phone designed from the start for wideband audio, I think it would offer at least some improvement.
EDIT: I'm going to copy this last paragraph to the feature request forum and if anyone wants to further discuss this let's do it there, so we don't hijack this thread.
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