What happens to the 70% of calls? What do you receive from the network? error, busy or silence?
They are not going through the PBX, on my telephone screen it says "ISDN Line Released Register on Timer"
SIP ALG off on the router
SIP ALG is disabled.
Keep Alive needs turning on maybe
Keep Alive is also turned on
Does it happen if no one is on the phone? ie, no one on a line and a call can call in ok? 2nd call doesn't get through or is it just random?
Yes, it is random actually, sometimes it goes through, but more percentage of the calls don't go through, it happens even if Lines are not in use.
Trace is the way forward. How many SIP Trunks have you got? Can you definitely have more than 2 concurrent calls? Our provider gives us 2 SIP Trunks as standard and I have to increase them to what the customer requested on the install, sometimes Ive forgotten and wondered at the end of the day why the phones are quiet!
I have done a packet trace, in the FW Side I cannot see any SIP Packets, it seems that it is blocking the packets, but I already allowed all traffic to go through because it is only in lab. Our provider gave us 2 SIP Trunks too.
A pattern will emerge once you narrow down the possibilities and we can help more.
Thank you very much for the response!!
RR