View source for Sip poke noanswer: Peer 'XXX' is now UNREACHABLE!

'''Description'''

In sip.conf there is an option for every peer called qualify.
If qualify=yes or a numeric value, then asterisk will sometimes poke this peer by sending a "SIP OPTIONS" request to phones or other pbx's.

If they do not reply on time, they will be considered unreachable, and this message will be printed on the asterisk CLI.

When the phone is back online (first time it replies on time) then asterisk will tell you Peer 'XXX' is now REACHABLE, if we got a reply from the phone, but not on time, the message Peer 'XXX' is now too LAGGED will be printed on the CLI.

The timeout is set to 2000ms by default. (If you specify qualify=yes).
But you could also set it to any other value.

e.g. qualify=3000


'''Reasons for seeing this message:'''

When a phone is rebooted, or when a phone hangs, or when its shut down this message might pop up.

(Or when there is a too big delay on the network).

If all your phones become unreachable at the same time, its probably your asterisk server that has network problems instead of the phone.

When a phone is unreachable, asterisk will not try to call it. (So you might want to set this value not too low, or you might want to completely disable it).

If the phone that has unreachable messages all the time is behind a NAT, it might be that the UDP timeout is set too low on the firewall.


Pasted from: http://www.asteriskguru.com/tutorials/peer_is_now_unreachable.html