DynDNS and VoIP

Just found an interesting situation regarding my VoIP phone. It might warrant some further investigation.

I took my Polycom phone home and put it behind a TrendNet router. Normally, this phone is connected to Broadsoft.

I happen to use DDNS so that I can get a URL to point to this router. But as soon as I enable DDNS, the Polycom phone quits. If I disable DDNS and restart the phone, it works again. I tried this a few times and I can duplicate this situation. so I am sure DDNS is interfering with the VoIP's DNS. Must have something to do with STUN.

Lession learned - don't enable DDNS at the router if you intend to use VoIP to Broadsoft.