[VoIP] What does this asterisk warning mean?

[Jack Ryan]

Hello all,

I added a dual port SIP ATA to asterisk and I get the following warning:

[Apr  3 08:52:27] WARNING[12462]: chan_sip.c:12741 handle_response: Remote
host can't match request NOTIFY to call
'2d4b898872ff215b5d58a92938d7f76a at ...'. Giving up.
The IP address is that of the asterisk server. The ATA otherwise appears to
be working.

Thanks

Jack