I am setting the minimum accepted registration expiration on GVGW to 120 seconds as a trial. The gateway’s default minimum of 60 seconds had been in place since launch.
It is recommended that users set their minimum value to at least 120 seconds. UAs attempting to register with a shorter interval will get a SIP 423 “Interval too brief” response and are expected to send another registration that conforms to the server’s minimum.
This is standard SIP but not every UA implements the standard correctly. Also there could be some misconfigurations where users have set a maximum interval lower than 120 which would prevent them from registering.
A 60-second registration timer causes the client to refresh at 30 seconds, which is grossly excessive considering that the majority of devices doing this haven’t changed their IP addresses in weeks or longer. Even as a keep-alive mechanism, a 30 second refresh is unnecessary. UAs needing NAT keepalive should use the appropriate option and not abuse SIP REGISTER for that purpose.