Extension can make, but not receive calls

[crofrout]

I have setup a number of extensions, all of which are working flawlessly except one - and I cannot figure out what the root cause is.
The SIP extension in question serves a Cisco 7960 phone (whereas all others serve 7970s). I went through the various steps to configure the phone and it is able to make calls as desired. No Issue there.

However, I am unable to call the extension. It seems like the phone is not connected, which does not make any sense, since it can make calls through the extension.
sip show peers shows:

Name/username Host Dyn Forcerport ACL Port Status
838 (Unspecified) D A 0 Unmonitored

which is different from all other phones where it shows the IP address of the phone.
The extension's settings (configured through the UI) are:

[838]
deny=0.0.0.0/0.0.0.0
secret=**********
dtmfmode=rfc2833
canreinvite=no
context=from-internal
host=dynamic
trustrpid=yes
sendrpid=no
type=friend
nat=no
port=5060
qualify=no
qualifyfreq=60
transport=udp
encryption=no
callgroup=
pickupgroup=
dial=SIP/838
mailbox=838@default
permit=0.0.0.0/0.0.0.0
callerid=xxx <838>
callcounter=yes
faxdetect=no

Which is the same as all other extensions (except for the numbers of course).

I am pretty much lost where to look. Any help would be appreciated.

[navaismo]

I bet that if you turn on the qualify in the console instead of unmonitored you will see UNREACHABLE. And that will be the cause of your issue.

About your statement that the peer can make calls it is because send and receive are two separated things. When the peer send the call to the server it send the data(IP,Port,Number etc) it knows where to send it. Receiving calls means that the server must know the IP address and port of the peer to send the call and since your phone is not registered the server fails to reach the ip address of the phone.

I always say that cisco 79XX are a ralley crappy thing to use with asterisk Yealink is way better than those models, but people keep using cisco 79XX because the brand.