SIP Calls Drop After 15 Minutes –
CheckPoint 1100 Appliance
There are many different reasons why SIP calls drop – if they regularly drop after a consistent period it’s very often a faulty SIP session timer or failure to send keep-alive packets. There are others however and this article highlights a parameter, which if set to false, will make Checkpoint 1100 appliance SIP calls drop after 15 minutes or another fixed period of time.
The reason is down to the fact that the CheckPoint periodically changes the port which the SIP messaging system communicates over. This means that the SIP re-invites and are not received by the phone system behind the firewall and the call will end after the remote side has not received a reply to any of the INVITEs sent after the specified time-out period (15 minutes in this case).
There is a boolean parameter in the 1100 under Device -> Advanced -> Advanced Settings named “Sip Service – Accept connections to registered ports” which is set to false by default:
Set this parameter to true and all should be well!
Notes: This is an issue across many firewall vendors. For example the SonicWall equivalent parameter is named “Enable Consistent NAT.”