Debug and/or test for which ports are open or blocked on a Sonicwall TZ105 in a site-to-site VPN

I have two Sonicwall TZ-105 with a site to site VPN between the two, however I'm having issues with the VOIP phone system.  This happens for both sites: the phone rings and shows extension, but nothing is heard on either end.  The tech with the VOIP system says ports are blocked.  I don't believe they are between the site-to-site VPN.  Is there away to debugging and/or test for ports that are open or blocked on this site-to-site VPN?

Thanks,
Jim
youritstaffAsked:
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gheistCommented:
Enable log of all rejected/dropped packets on firewall, then check of drops where communication is disrupted.
PhonebuffCommented:
Voice would be RTP protocol which is a UDP transport on ports 10000 - 20000.   An if your SIP (5060 & 5061) is working, and it is if you see caller ID and the handset rings then RTP is mostly likely blocked.

There are a number of port scanners available have a look around with google.  But NMAP but be one if the better / easier to use -  http://searchsecurity.techtarget.com/tip/Nmap-How-to-scan-ports-and-services
masnrockCommented:
You need to clarify: Is the issue just with incoming calls on extensions from the opposite office, or is this a problem with incoming calls in general, including from the outside to the location with the PBX? If it is a problem with incoming calls overall, then you need to check the WAN > LAN access rules and open up a sufficient range of ports like Phonebuff has mentioned.

Also, I am assuming that the second location has a separate subnet, and does not use DHCP over VPN. Please confirm whether this is the case.
youritstaffAuthor Commented:
Thank you everyone for your assistance the issue was with the VOIP system/server, which was resolved after a rebooting it.

Jim

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youritstaffAuthor Commented:
The tech had made changes on the VOIP server, but never rebooted it after making said changes.
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