How long for a VoIP call to tear up?

[hxmengmetro]

All,

I'm trying to figure out how long it will take for the call drop when the WAN drop starts. For example, you have one call from cisco phone at one site and calling to another site's cisco phone over the WAN. And then WAN suddenly drops. I know when the WAN drops, you might hear silence in the call, but the call is still established. But if the WAN connection is down for enough time, the call will be teared up. So what's the hold-on timer for the protocol to tear up the call?

I was thinking about the keepalive time for phone in call manager, but that one is actually for registeration not for the call tear up. I'm trying to figure out what's maximum WAN down time we can have to still have phone call ongoing.

Any idea?

Lou

[paolo bevilacqua · Accepted solution]

Can vary by system, but in the order of 10 - 20 seconds. Some protocols are better than others to detect failures.

[Brandon Svec · Accepted solution]

This may not directly answer your question, but is a very academic analysis of the topic that may be helpful:

http://eeweb.poly.edu/faculty/yongliu/docs/udptcp.pdf