#13 answer with no connection

[Alex Lee]

hi all,

I'm trying to connect myphone with an analog phone
through a gatekeeper and a PSTN gateway.
For intance, when I use MyPhone to call the analog one,
I got no problem with it, perfect! However, when I use
analog phone to call MyPhone, MyPhone did ring, and
then I press "Answer", but the analog phone is still
calling. That means MyPhone cannot establish a
connection with analog phone. But when I press "Hang
up", it works fine again.

Can anyone give me some idea?
Thanks a lot.

Best Regards,
Alex