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?

Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Enable log of all rejected/dropped packets on firewall, then check of drops where communication is disrupted.
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 -
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.


Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
youritstaffAuthor Commented:
The tech had made changes on the VOIP server, but never rebooted it after making said changes.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Voice Over IP

From novice to tech pro — start learning today.