i am using Brekeke PBX with Vonage, it works fine, Brekeke has the Configuration Manual on their website, in which is http://www.brekeke-sip.com/download/pbx ... age_en.pdf
hope it's helpful

Can you post any error messages from Tomcat?

Please see changes in blue matching patterns: to sip:9(.+)@ deploy patterns: to sip: 1(your area code) $1@172.16.1.25:5060 example:deploy patterns: to sip: 1650 $1@172.16.1.25:5060 and add one more OUT Priorities set the Priorities number which is smaller than 100, example Priorities 50 matching ...

or your Thru Registration may be off.
go to Brekeke SIP Server Admintool > Configuration > SIP
set Thru Registration is on.

http://www.brekeke-sip.com/bbs/viewtopic.php?t=2610
check that link above. it may help, good luck

check this link http://www.brekeke-sip.com/bbs/viewtopic.php?t=2662