Invitation Problem

Dear Sir

I have a problem which happend with some of my customers:

- some times, when this customer want to dial a certain number, Its ringing ok in the both sides and they establish the RTP session ok.

-another times, when one of the members want to make a new call to any number in the system, Its take a very long time in ringing, or not ringing at all.
Note: they may finish a call and want to establish a new call after some time, at this time the problem may happend.

So, What is the reason for this problem, may be loss in invitation packets?
please try to help me in this problem.

Amr

we are using brekeke SIP server 2.0.7.2 after upgrade from 1.5.3.0 on slackware 10.2. after upgrade SIP server our customers reported to us problems with incomming calls. customers have draytek vigor 3300v gateways. other customers gateways and phones doesn't have this problem. only draytek vigor3300v.
problem:

incomming call from czech number (national numbering plan - 9 digits) is OK.
incomming call from slovakia (00421xxxxxxxxx). OSS send INVITE to customer gateway, but gateway doesn't send 100 Trying. OSS send 4x INVITE and session end with error code 487 - session timeout.
i tried restart OSS and after restart was incomming calls from slovakia ok. 5-7 hours after restart we have same problem with calls from slovakia.
all customers gateways have public IP address.

do you have some ideas? old oss works without any problems 1 year.

we are using 3rd party db on the mssql2000 with sp4.

----------------------------UPDATE 3.5.2007 ----------------------------

Problem fixed. Draytek 3300V have problem with RPORT parameter. Add 'rport' parameter (send and receive) must be turn off.



After turn off rport, Draytek works fine.