This is what I found after couple evenings and coupe hours with OOMA and Arris support.
Not much help from either.
What I found after experiments is that for this particular problem:
- DMZ does not work
- Port forwarding does not work
→ LOW level of firewall works!!!
Arris support mentioned SIP ALG problems today so I started looking for more info:
“Every ITSP that I have ever used has recommended disabling any SIP ALG in consumer class NAT/routers.
OnSIP staff told me that unless I have business-class gear from Cisco or Juniper don’t use any ALG. Let their NAT traversal solution handle the issue.”
Many of today’s commercial routers implement SIP ALG (Application-level gateway), coming with this feature enabled by default. While ALG could help in solving NAT related problems, the fact is that many routers’ ALG implementations are wrong and break SIP.
Darveter >>> Moto info below might be old because SIP ALG shows as if it is possible to disable now.
Will try it tonight. I hope I do not have to disable NAT and go to bridge mode. What
is the point of having combined device if I disable the router in it.>>>
Models: SBG6580 (SurfBoard Extreme Wireless Cable Modem Gateway)
No Registeration possible behind NAT as the device changes Call-ID and causes the responses to be discarded by SIP clients/ATAs
No Solution at this time (SIP ALG, called SIP Pass Through, can not be disabled) .
Must disable NAT and put the device in bridge mode. (See this guide)