cancel
Showing results for 
Search instead for 
Did you mean: 

Line quality Sip to PSTN - incoming sound

fotobits
Rising Star
Posts: 584
Fixes: 1
Registered: 23-06-2007

Line quality Sip to PSTN - incoming sound

My SIP to PSTN calls are good volume, however, the incoming voice frequently switches from loud to soft during a call.
I notice that my line's Output Power - downstream is 19db.  Could this be the cause and is it, therefore, a line problem?
Regards
6 REPLIES
petermaughan
Grafter
Posts: 83
Registered: 06-04-2007

Re: Line quality Sip to PSTN - incoming sound

Hello fotobits,
I think you would need to say something about the VOIP kit that you are using and where you got the 19db measurement from, in order to inform any reply.
My instinct would be to say that 19db downstream output power is nothing to do with your problem.  Decibels is an analogue measurement, whereas VOIP is a digital transmission.
Peter
fotobits
Rising Star
Posts: 584
Fixes: 1
Registered: 23-06-2007

Re: Line quality Sip to PSTN - incoming sound

Many thanks, Peter.
I suspect I may have found the problem.
Today I connected my 'phone's base-unit to the alternative telephone socket in my 'phone adapter......looks as if this has cured the problem.  I'll know better tomorrow.
In the meantime, the router is an Zyxcel P-660H-D1.  In Bandwidth Management I've set VoIP traffic to "high" priority, "e-mail" traffic to medium priority and "www" traffic to "low" priority.  WAN rule for VoIP I've set to 100Kbps although I'm querying this value with Zyxcel support.
The 'phone adapter is an Zyxcel P-2002L, mostly default settings.  Compression G711, Expiration Duration is currently the default of 3600-secs, 'though I have tried lower values down to 600-secs, ie re-registration every 5-mins.
I suggest we see if the switching of sockets does the trick, otherwise, I'll be hoping for comments tomorrow!
Regards.....Noel
fotobits
Rising Star
Posts: 584
Fixes: 1
Registered: 23-06-2007

Re: Line quality Sip to PSTN - incoming sound

....sorry, Peter, I didn't answer your question!
The Output Power - downstream came from the router's Diagnostics - dsl line and is to do with noise.
I understand that max of this value is 15db and <15db is better.
However, I suggest we await my further tests tomorrow when I'll be using the SIP-to-PSTN connection.
Regards....Noel
fotobits
Rising Star
Posts: 584
Fixes: 1
Registered: 23-06-2007

Re: Line quality Sip to PSTN - incoming sound

I have experienced very good quality voice today using SIP-to-PSTN, both ways, so I guess it was a poor connection with the adapter.
However, my router went offline this afternoon and didn't re-connect.  I have a strange feeling that this is after the receipt of a PSTN call.  Or perhaps I'm losing my marbles!
Regards
PS Thanks for your interst, Peter.
petermaughan
Grafter
Posts: 83
Registered: 06-04-2007

Re: Line quality Sip to PSTN - incoming sound

Hello Noel,
I'm glad you've got your sound quality sorted out.
My own router (Speedtouch 716v5WL) goes offline and resets itself sometimes and looses its VOIP configuration.  I'm intending to raise it on this forum when I have done some more diagnosis.  In my case it happens when I try to watch streaming video from the BBC News website, which I think is very strange behaviour indeed.
I guess there could be any number of reasons why your router is going offline.
Peter
fotobits
Rising Star
Posts: 584
Fixes: 1
Registered: 23-06-2007

Re: Line quality Sip to PSTN - incoming sound

Peter, I'm interested to hear that you're having registration problems!
In my case, I think but I'm not sure, that the router, a Zyxcel P660H-D1, loses the internet connection and the adapter, a Zyxcel P-2002L, then loses it's registration.
Like you, I'm monitoring this currently and I feel it happens following the receipt of a call from a PSTN number!
I don't understand why the adapter doesn't re-register automatically, let alone why the router is disconnecting.
Once I can identify exactly what's happening I'll let you know.
I'd be interested to keep in touch on this one.  A new string?
Regards.....Noel