Defensively installing a VoIP telephone adapter

Recently, fellow Computerworld blogger Robert L. Mitchell has been writing about about Vonage and Ooma, two independent VoIP (Voice over IP) providers. As a relatively new Vonage customer I carefully read the account of his problems and subsequent debugging.

Mitchell added the Vonage telephone adapter (V-Portal) to his network exactly the way Vonage instructs.

I would never do that.

Assuming your broadband modem and router are two separate boxes (rather than a single integrated unit), Vonage instructs you to install their box between the modem and the router. No doubt they do this to insure the best VoIP performance. It also makes their tech support easier, the V-Portal is only dependent on the broadband modem. Any problems with the router aren't their problem.

From a Defensive Computing perspective, however, this is a mistake.

All the computers on a Local Area Network (LAN) have to depend on the modem and router; there's no way around this. But, do you really want every computer on your network to also depend on the telephone adapter? Do you want a problem with the V-Portal to knock the entire network off-line? I don't.

Mitchell disagrees, writing

... placing the V-Portal behind the router limited the unit's ability to give preference to voice traffic as opposed to, say, my daughter's viewing of YouTube videos. That can affect call quality. The best choice, therefore, is to put the V-Portal first in line behind the cable modem ....

We have different priorities. I can not risk all the computers on my network being affected by a VoIP related problem. To me, the computers are more important than a single phone line.  

And, while having the VoIP box behind the router (that is, having a setup of broadband modem -> router -> VoIP telephone adapter) does not let the Vonage box give preference to voice traffic, you can accomplish the same thing by having the router give preference to VoIP traffic.

In fact, using a router for prioritizing things gives you much more flexibility. You might, for instance, set VoIP to the highest priority, computers used by adults to a medium priority and computers used by children to a lower priority.
 
This is not to pick on Vonage at all. Previously, I used a competing VoIP service from AT&T called CallVantage where the situation was exactly the same; AT&T also wanted their telephone adapter directly connected to the broadband modem.

More on prioritizing data traffic, officially known as Quality of Service, next time.