Incoming call sometimes ring twice and picking up handset does not answer the call

Asterisk V.
FreePBX V. 2.8.1
SIP Provider: Broadvox
Endpoint: Cisco 7940G w/ SIP 8-12 firmware


I wish I could be more specific here, but the problem is difficult to describe and searches have turned up nothing.

Here goes: Approximately 2/3 of my incoming calls work perfectly fine.

A few weeks ago, we started having erratic behavior on incoming calls. 1/3 of the time, an incoming call will come to all phones twice, and if we try to answer, most of the time it will just sit there saying “ringing” and never actually picks up.

I am looking through the logs and console but can’t find anything wrong. I’m betting it’s a NAT issue but not sure what. I’ve forwarded port 5060 and 10000-20000 (UDP) on my router and enabled SIP-ALG. Set the external and internal IP on the Asterisk SIP settings.

I’m sure it’ll be something stupid, but I’m just not sure where to look, and its not consistent, so its hard to pinpoint. Any time I call from my cell it goes through fine and happens at random.

Any tips appreciated!

Hi I guess you figured out already, right? Can you share me some info? Since I got exact same as your description, and no clue from googling…