What is port shuffling and how do can it be resolved?
- NAT Ports
- Port Shuffling
Port shuffling indicates that the assigned NAT ports are changing frequently. This is due to session time out on the firewall or router in use. For most business class firewalls this can be modified by changing the UDP timeout for non-SIP over TLS (non-SRTP) devices. In cases where SIP over TLS (SRTP) is in use, the TCP time out should be modified.
These settings should be modified to match the registration timers on the phones, which call out to register every 11 minutes, or 660 seconds.
If session timeout values are set too low (below 660 seconds) the following issues can occur:
- Dropped calls
- Registration issues
- Call misrouting
- One way audio
- No way audio
- Unable to retrieve calls on Hold