VOICE GATEWAY AND PSTN BAD VOICE QUALITY

[chrysostomos1980]

Hi all

We have a strange issue and we need your opinion

Incoming calls or outgoing calls to PSTN have very bad quality.. We use PRI.Note that not all the calls have problem.Its some times and occasionally..

We have checked the controllers and are clear..where we have to look for that issue..

Calls flow:

CUCM-GW via h323 -PSTN-via PRI

ITS 6 years implementation and the problem appeared now

[D_Lebedev]

Hi,

What kind of "bad voice" ?

Is it echo like,or robotic voice,slow motion voice? what exactly?

CCM ver?

IOS Ver?

I have faced with robotic voice when PSTN provider changed their station type without notice.

If you're sure no changes were made from your side,try to find out maybe provider did.

[chrysostomos1980]

Hi

One time when you are on the call everyhting its ok , and one time you have one way audio

[D_Lebedev]

I'm not sure about H323,but with MGCP it may be caused by misunderstanding PRI Signalling.

Please,see attach.

[Senthil Kumar Sankar]

Hi,

If you have multiple T1's/E1's, try to find whether the calls which are going on 1 single T1/E1 giving issue.

Place test calls and if you face audio issue on that call, go to the voice gateway and check on which Interface the call is going. This can be done by giving the command

show isdn active serial 0/0:23.

Then try to analyze and find that is that only 1 single T1/E1 is giving issue. This will help us to identify if there is any misbehaving T1/E1

Regards,

Senthil

[chrysostomos1980]

Hi and thanks for your reply

If i issue the command

GW#show isdn active serial 0/0/0:23

ISDN Error: Illegal Interface Se0/0/0:23

Also if we have a misbehavibg E1 ISSUE then what steps we have to follow

[acampbell]

Hi,

Can you post the show runn from your gateway

Regards

Alex

[chrysostomos1980]

Hi Alex

See attached file

[acampbell]

Hi,

The config looks very good to me

The H323 is bound to an interface so that eliminates the usual oneway transmission

config error.

You also say that the system has been in for quite some time and just

recently suffering this issue.

I think you need to take thisup with your ISDN service provider

You could have some dodgy chennels in your link at their mux end

One other thing to clarify.

Your router has 2 E1s

0/2/0 is maked as OLD is it still in service.

clear your counters - all interfaces

show controller E1 0/0/0 brief

Look to see if any errors are rising

Repeat for E1 0/2/0 - (If it is still in service)

show controller E1 0/2/0 brief

Regards

Alex

[Senthil Kumar Sankar]

Hi,

You have E1 PRI, so you have to give 15th channel instead of 23rd channel

show isdn active serial 0/0:15

If you see there is an issue on one single E1, then you have to chase the ISDN Provider to check

Regards,

Senthilk

[chrysostomos1980]

Hi to all

Thank you for your answers

My opinion is also that the problem is on ISP site

Then if we found that specific channels have problem then the only steps that we can do are to block (ISP must block) these channels?

Regards