VoIP phone which cannot be called (no incoming calls)

Hello,

I have a problem with one phone (snom 300) in a voip network based on freePBX 2.1.1.
I added 8 phones to the network. Settings were changed for each one of them in a same way. I add extension number (1604) and inbound route for it as well, but…i cannot call this number, i get a message: service 1604 unavailable. But i can make calls from that number(1604) to any other phones! everything seems to be fine, except of that you can call that number(1604) from other phone.
Settings on a phone are corrrect. I set up that extension number(1604) on another phone and… it’s the same problem! so it has to be sth with freePBX settings, sth had to be added to the freepbx settings, sth wasnt cleared and there are results…

here are few lines from asterisk log file (freepbx -> tools)

[code:1]
Sep 25 11:43:11 VERBOSE[4848] logger.c: – SIP Seeding peer from astdb: ‘1604’ at

[email protected]:x for 3600
(…)
i’ve found this line in: /var/log/asterisk/full
(…)
Sep 25 11:43:16 DEBUG[13275] db.c: Unable to find key ‘SIP/1604’ in family ‘cfb’
(…)
Sep 25 11:43:28 VERBOSE[4848] logger.c: – Unregistered SIP '1604’
Sep 25 11:43:28 DEBUG[4836] chan_sip.c: Checking device state for peer 1604
Sep 25 11:43:28 DEBUG[4836] devicestate.c: Changing state for SIP/1604 - state 5

(Unavailable)
Sep 25 11:43:28 DEBUG[4836] chan_sip.c: Checking device state for peer 1604
Sep 25 11:43:28 DEBUG[13276] app_queue.c: Device ‘SIP/1604’ changed to state ‘5’

(Unavailable)
Sep 25 11:43:28 DEBUG[4848] chan_sip.c: **** Received REGISTER (2) - Command in

SIP REGISTER
Sep 25 11:43:28 VERBOSE[4848] logger.c: – Registered SIP ‘1604’ at x.x.x.x port x

expires 3600
(…)
[/code:1]

do you know where can be a problem?
thx