Incoming phone calls drop after being answered

[3397premier]

We are having an issue where some of our phone calls answered from the queue are being dropped. Drops after 4-8 seconds. When we answer we do not hear anything and then it drops. It is very random as a good portion of the calls received work just fine.

We called the person back and they say when they calls us it does not ring or anything so they hang up and try again and then they may get through. It sounds like the call continues on until it gets to a phone and then due to silence it will hang it up automatically.

We are using a Dell server with 2008 R2, OneNet as our SIP provider. 3CX is setup with these options:

VOIP Provider:
PBX Delivers Audio ON
Support Reinvite OFF
Support Replaces ON

Phone/Extension:
PBX Delivers Audio ON
Support Reinvite ON (tried with it off, same thing)
Support Replaces ON (tried with it off, same thing)

We are using Polycom 450 phones. I know it may be a 3CX setting adjustment, but just not sure which one to make.

No issues on outgoing calls, transfering or conferencing.

Thank you,

 

[paul.hadley]

Do you have a server activity log for a failed call.

I had a similar problem with an Orbtalk trunk dropping, or failing to ring through on a call.

My general experience of intermittent faults is that they are caused by either a firewall or the service providers setting, firewalls most common.

Every time I have had a configuration issue with 3CX it has led to permanent problem rather than an intermittent one.

Might be worth checking your router logs at the time of a failed call.

 

[3397premier]

Thanks for your respond Paul. We just had problem about "ring back" when clients called to 3cx (either toll free or local DID), turn out the it was the SIP Provider problem. all they have to do is remove the trunks and put it back in. But we still have problem about the drop call.

Quick question:
1/ Is it safe to setup 3CX connect directly to internet modem or it has to go through firewall (right now we have internet modem connect to cisco asa 5505, then connect to switch 1 which has 3cx server connect to it also)

2/ The sip provider we are using isn't in 3cx list, so I don't know is that why it doesn't work properly?
We use OneNet as our Sip Provider, before that we use Bandwidth, but they dropped connection at least twice a week.

I'll try to check the router's log at the time of a failed call

1/ I am interest to know how is your phone line setup, please share if you can, thanks
We have 2 separate internet connection, 1 for voip and 1 for data. We have all switches connect to switch 1, on switch 1 we have 3cx server connect and cisco router. The cisco router then connect to internet modem.

 

[netswork]

is the router doing inspection or fixup?

 

[Nick@Troosters]

Hello,

I'm having the problem that the HOLD / RESUME function does not work asit should.
I turned off SIP inspection on my ASA 5505.
What settings did you make on your CISCO to make it all work fine ?

 

[SY]

VOIP Provider:
PBX Delivers Audio ON
Support Reinvite OFF
Support Replaces ON

Support Replaces OFF should resolve the problem.
What was the reason to change it to ON?

Thanks