SIP audio fine on USG60, Fails on FLEX 200H

Smasher

I have a Zyxel USG 60 firewall and a new Zyxel Flex 200H firewall that are configured identically. VOIP trunks work fine on both, as do IP extensions within the same internal network as the IP PBX box.

However, SIP audio to, from, or between IP phones on external networks work only on the USG 60. Switch to the identically configured FLEX 200H, and the audio on external phones stop. Calls are set up and the phone rings, but that's it. Switch back to the USG 60, and SIP audio is immediately restored.

I have painstakingly configured the FLEX 200H to have the same NAT, Security Policies, and other configurations to be exactly the same on both devices.

Is this a hardware issue requiring an RMA or return of the unit to Amazon for a refund? Any suggestions?

PeterUK

Currently the H models don't have ALG SIP support in V1.10.

You could check the traffic if you need to allow a given port by Virtual Server

Smasher

ALG SIP support is turned off, so why would it matter?

PeterUK

Do you see any blocked traffic the making calls 

Smasher

Problem resolved. ALG was turned off in the 200H. SIP audio restored by turning it on, so you were on the right track. Thanks.