Fragmented UDP packets often do not cause a problem, but this is entirely dependent on the client’s network infrastructure. Because not all SIP packets are the same size, so far, we’re mostly seeing this happen on specific events that create the largest packets. If you start to see a client that has any of the following problems, it makes sense to see if this is the problem they’re running into. - Internal transfers do not ring the other person’s phone or fail.
- Intercom from one device to another does not work correct.
- Incoming calls do not ring devices on new clients or after network changes have been made.
The easiest troubleshooting steps is to simply set a couple of their devices to TCP and see if that resolves the problem. For more in-depth troubleshooting, a packet capture can be performed to see if INVITE packets are greater than 1480 bytes in instances of failure. |