For some unknown reason, in the past few weeks our ViaTalk VOIP phone started hanging up after *exactly* 10 minutes. After a little bit of searching I found this page which under the promising heading of “VoIP call disconnects after 10 minutes” had a link to this document.
I already had the VOIP unit set up in the DMZ, so that wasn’t the problem. The document also talks about turning off the “SIP ALG” method. Well, buried deep on the Dlink DIR-655 router’s Advance > Firewall Settings page, I found a SIP checkbox under the Application Level Gateway (ALG) Configuration section. I unchecked it, saved the settings and this seems to have fixed the problem! We’ll see if it stays that way. I’m hopeful. Thought I’d post this in case anyone else runs into this issue.