Is it possible to see UDP Timeout and SIP-ALG in pcap?

edit

You can't, but if you capture on both sides of the device with SIP-ALG and UDP session timeouts, you might be able to deduct from the UDP packets if SIP-ALG is used. By analysing a lot of sessions with different idle times in the UDP traffic, you might also be able to guestimate the UDP Session Timeout.

However, it is far more easy to just check the configuration or if you don't manage the device yourself, ask the administrator of the device to provide you those details.