ISDN vs VOIP quality

JacquesOmeister

JacquesOmeister

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Hi Everybody

Firstly I want to explain my PBX setup

Yeastar MyPBX Standard (telephone system) - Very stable system and easy to use
4x ISDN lines (BRI)
Neotel NeoBrand Fibre 10Mbps

I tested (making calls) this morning and the quality of ISDN sounds much better then the VOIP(Neotel). Are there a way to make my VOIP calls sound just as good as ISDN voice calls?
 
What codec are you using on the Neotel SIP trunk? Is the Neotel link dedicated to voice or are you running data over it as well?
 
I am using the following codecs - u-law,a-law. Yes I am running data on Neotel link, but the users are using very little bandwidth...
 
Have you tried g729?

I was under the impression that if you had a Neotel link and made use of their VoIP service they would apportion a dedicated section of the link to just VoIP? Might be worth asking your account manager.
 
I am renting my Neotel line through Mweb and using Mweb Talk. I haven't tried G729, does codec G729 make a big difference?
 
G279 is optimized for good quality and low bandwidth usage, but if you say your link is under utilized it may not be the solution to your problem.

Unfortunately I'm not familiar with the MWeb talk setup so can't really suggest anything else other than testing another VoIP provider to see if you have similar results.

What exactly is the perception that the quality is lesser on VoIP?
 
Well at the end of the day I want my VOIP to be 100% like analog/ISDN lines. I and my users don't want to say every time I cant hear you, can you repeat that. I don't think it is a bandwidth problem, data line latency is very low and ping very good to mweb server (5ms). Only 5 hobs to Mweb IP. I think it must be PBX or codec, but I can be wrong? Any other suggestions
 
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Would like to add my 2c worth,

See MTalk supported codecs (old article, g722 is supported now)

Telkom ISDN is alaw. The problem is Mweb's interconnect to Telkom is not - as such calls sound crappy to & from Telkom numbers regardless of what codec you're using to Mweb.
 
JacquesOmeister said:
Well at the end of the day I want my VOIP to be 100% like analog/ISDN lines. I and my users don't want to say every time I cant hear you, can you repeat that. I don't think it is a bandwidth problem, data line latency is very low and ping very good to mweb server (5ms). Only 5 hobs to Mweb IP. I think it must be PBX or codec, but I can be wrong? Any other suggestions
Click to expand...


Hi,

If you want your calls to sound exactly like PSTN on ISDN then you need to configure your equipment to use ALAW codec. Assuming your provider similarly passes the call through to Telkom et al in ALAW then it will sound exactly the same. (Since its exactly the same codec that ISDN uses).

Steve
 
Hi guys.

I also have a Yeastar myPBX Standard (v4). Could anyone recommend a good, compatible softphone client for iPhone and Android. To be used only on the premises (local network) - so should connect to myPBX SIP.

Thanks!
 
Isdn is near cd quality audio and is extremely quick interms of connecting. I personally love isdn. Where as voip uses codecs to compress the audio and depending on your hardware that decodes it. There are many factors involved that degrages the quality of the audio further. You need a dedicated bandwidth management to run an office of voip phones. Otherwise some bloke will will just kill the phone because his dowloading a large file. They both have their strengths
 
ISDN uses the G711 codec. The reason it sounds better is because it uses circuit switched networks and not packet networks (internet). There is no jitter on Circuit switched networks. If your internet link is good, there should be no difference in quality
 
This 10 meg fibre is this a fiber cable install or did they put in a wireless radio, I had a customer that paid for a fibre but Neotel installed a Wireless link using Skywire, call quality is shocking.
 
If the last mile is not fibre but ISM band wireless you will have varying results since it is interference prone...
 
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