Noisy ring back tone when transferring PRI calls

[Lynx77]

Hi All,

We have a CS1000E connected to an MSC via PRI (EuroISDN). We are facing an issue when transferring a call connected to a GSM phone from one phone to anther..
The GSM phone user is hearing noisy ringback tone while being transferred. No noise while talking or while hearing ringback tone if the call hits an extension directly without transfer. The noise is only heard on transfer.
Extensions are IP phones i2004 agents – Latest firmware installed. We are using a CS1000E Rls5.5.
The problem is faced on incoming and outgoing calls.
I found a thread addressing a similar issue "Inbound noise problem" but it was an 81C and the problem we solved by changing the Conf/TDS NT8D17 card or its dip switches settings.
In CS1000E, tones are generated by DTRs in MGC cards 14 and 15. I assume it is not an MGC loadware/hardware issue since the problem was also faced on the same site using CS1000S (before upgrading to CS1000E).
Could it be DChannel, PRI RDB or Trunks, MSC settings? Or can it be related to switch settings on the chassis i.e. ringing amplitude/frequency (same chassis are used after the upgrade)?.

Any help is highly appreciated.

 

[johnpoole]

could be a bad def in ftc, i would replace the card (conf/tds) before i look at ld 56

john poole
bellsouth business
columbia,sc

 

[Lynx77]

Hi John,

It is a CS1000E - No Conf/TDS cards.

Just discovered more info about site. The symptom appeared when the MSC added a prtocol converter:
> ISDN PRI - ISUP Gateway (IGW-P) produced by TietoEnator.
to convert EuroISDN (PABX side) to SS7 (MSC side).

Here is the problem. But any experience with converters and is it possible to change some E1 settings to resolve it?

Thanks.