Nextiva Phone System and Sonicwall NSA 2400

We have a client that recently installed a Nextiva Phone System http://www.nextiva.com/. The Nextiva phone system uses Cisco 303G SIP Phones that connect the Nextiva's phone switch in the cloud. When we contacted Nextiva for help on configuring their phone system with the Sonicwall NSA 2400 their support indicated that their phone system is NOT compatible with Sonicwall firewalls. They do ship a Linksys Wireless router that does work with their phone system, but we wanted to use the Sonicwall to leverage the enhanced security featuress and automatic failover to a backup Internet line. We found a combination that works with the Nextiva phone system and the Sonicwall NSA 2400. Here are details:

1. Sonicwall NSA 2400 with the firmware 5.6.2.1-4o. This SIP enhanced firmware is specifically designed to work with VoIP phones. This firmware version is availabe on mysonicwall.com. Make sure that you use this version of the firmware, the latest version of the firmware will cause problems with dropped calls.
2. VoIP Settings. Under the VoIP settings, make sure the following items are checked:
1. Enable consistent NAT.
2. Enable SIP Transformations.
3. All other items should be left unchecked.
3. Outbound Firewall rule. If you're limiting outbound network traffic from the LAN to the WAN, create a rule to allows UDP traffic on ports 5060-5070 to the IP address of the Nextiva phone sytem.

Before making these changes we received complaints about dropped calls and difficulty dialing out. But, after the firmware was changed and we made these changes, the phone system has been very stable. Hopefully this post will help you get a Nextiva phone system up and running with Sonicwall firewall.