[cisco-voip] Suddenly can't make calls (it sound busy)

[MC_Vai]

Just last week I was able to make calls through VoIP,  
but suddenly I can't. If I dial the call is made but then a few seconds later  
(also I can't hear the call progress indicator) sounds as if it was busy.  
However, the other peer can make calls to my router.  
  
My config (relevant parts only):  
- - - - - - - - - - - - - - - - - -  
!  
voice-port 1  
!  
...  
!  
dial-peer voice 10 pots  
 destination-pattern 4010  
 port 1  
!  
...  
!  
dial-peer voice 100 voip  
 tone ringback alert-no-PI  
 destination-pattern 50..  
 session target ipv4:<OtherHostIP>  
!  
...  
- - - - - - - - - - - - - - - - - -  
  
  
What I've been able to debug so far:  
- - - - - - - - - - - - - - - - - -  
# show dialplan number 5010  
  
VoiceOverIpPeer100  
        peer type = voice, information type = voice,  
        description = `',  
        tag = 100, destination-pattern = `50..',  
...  
        translation-profile = `'  
        disconnect-cause = `no-service'  
        type = voip, session-target = `ipv4:<OtherHostIP>',  
...  
        Last Disconnect Cause is "1B  ",  
        Last Disconnect Text is "destination out of order (27)",  
        Last Setup Time = 2496017.  
Matched: 5010   Digits: 2  
Target: ipv4:<OtherHostIP>  
- - - - - - - - - - - - - - - - - -  
  
I was reading from  
http://www.cisco.com/warp/public/129/isdn_disc_code.html  
that there is a way of detecting the "Cause Code Origination Point"  
from the output of the command:  
# debug isdn q931  
  
but I can't find any similar command for my situation. I've tried with  
debug pots ringer  
debug dialpeer  
but the don't issue the 'Cause i =' output (used in the url above)  
  
Does anybody know the equivalent command or any other tip that can help  
me to debug and resolve my problem?  
  
Thanks a lot in advance for your help  
Highest Regards,  
  
Ed