byronb
join:2007-02-25
North Vancouver, BC | [General] Voip to Cellular
I notice the call quality of VOIP --> PSTN is as good as a PSTN call, whereas VOIP --> mobile can often be worse than a PSTN-->Mobile or Mobile to Mobile call. Am I "hearing things" incorrectly or is this generally true of VOIP, and if so, why? |
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CyberSultan
Premium
join:2006-07-20 | I do not notice the same issue with calls between VOIP and cell. Are you referring to a particular cell phone provider you have tested against or have you experienced this problem with multiple cell providers? |
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goodchefro
join:2007-02-21
Macomb, IL | The cell phone itself might be a factor, as well. Also, isn't the internet connection speed considered a crucial element in a good VOIP audio quality? |
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redshift
Premium
join:2004-03-23
Beverly Hills, CA
| reply to byronb
I would disagree to this as well. I call mainly people with cell numbers and my voip => cell calls are just as good as PSTN => cell. It may however be an issue with your particular voip provider as they may not have good interconnection with various cell companies.
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"So this is how liberty dies. With thunderous applause." |
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blohner
join:2002-06-26
Cortlandt Manor, NY
clubs:
 ·Vonage
 ·Optimum Online
| reply to byronb
Cellphone carries compress the hell out of their calls to squeeze more calls onto their Networks. That is at least true of most carriers on the US - I assume Canada is no different (my experience in Europe is much more positive)
The problem with voice quality arises if your VoIP link uses a codec with compression on Voip (e.g. G.726, G.729). Now you have
Phone->Compress->VOIP->Decompress->Carrier Link->Cell Compress->Cell Link->Decompress->Phone
Which is double compress-decompress and that can cause noticable call quality degration.
Using G.711 or another uncompressed codec I have no difference between VOIP->Cellphone and POTS->Cellphone (both are equally bad on accounts of the Cellphone)....
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I am addicted to speed --- OOL speed that is --- |
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byronb
join:2007-02-25
North Vancouver, BC | reply to byronb
I think what it is when I connect to a cell phone with a marginal connection (theirs) then the static and pops are amplified by the VOIP codec compression. |
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simlockboy
join:2006-04-25
u
| reply to byronb
I have been using a DOCK N TALK with SPA3102 for quite some time, and yes it is true wih G711 the voice quality is much better.
U should also check if ur DOCK N TALK OR SPA 3102 is getting over heated ??
For me i had to change the adapter to 220 V and due to it there was overheating and the call quality used to suffer
Please see to it u keep devices in a cool area
cheers |
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joako
Premium
join:2000-09-07
/dev/null
 ·AT&T U-Verse
| reply to blohner
said by blohner  :Cellphone carries compress the hell out of their calls to squeeze more calls onto their Networks. That is at least true of most carriers on the US - I assume Canada is no different (my experience in Europe is much more positive) The problem with voice quality arises if your VoIP link uses a codec with compression on Voip (e.g. G.726, G.729). Now you have Phone->Compress->VOIP->Decompress->Carrier Link->Cell Compress->Cell Link->Decompress->Phone Which is double compress-decompress and that can cause noticable call quality degration. Using G.711 or another uncompressed codec I have no difference between VOIP->Cellphone and POTS->Cellphone (both are equally bad on accounts of the Cellphone).... I was going to post the same thing. I think also the issue is GSM vs CDMA. CDMA EV-DO's default codec is 8kbps, there is an older "sounds worse" according to the "experts" 13k CDMA codec that actually sounds better.
GSM on the other hand, what you will find in Europe 99% of the time, doesn't have codecs which over-compress the Voice.
Nextel a few years ago also started to double compress voice, thats why Nextel subscribers sometimes sounds like robots.
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Am Heimcomputer sitz' ich hier, und programmier' die Zukunft mir |
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