asterisk users - Jun 2011 - Asterisk 1.6 - subscriptions.

Hi all,

I try to figure out why I have empty :
> sip show subscriptions
list in may asterisk 1.6.

When device is registering to asterisk I can see in log:
NOTICE[25603]: chan_sip.c:21518 handle_request_subscribe: Received SIP
subscribe for peer without mailbox: 1010

but
> sip show subscriptions
is just empty.

May it be the problem because devices are registering to asterisk from
behind NAT?

Regards,
Jarek