WiFi Calling ScreenI’m on Sprint in Nashville, which means in the area I live in (listed as best signal), I now have to rely on an internet connection in order to get (and sometimes place) phone calls. I’ve done Airave devices, call forwarding to a pseudo landline, GTalk/GVoice forwarding and most recently the built-in Sprint WiFi calling option, which seems to have had the best result as I actually get phone calls now.

One day last month my Sprint WiFi calling stopped working. It just failed with a red line through it. No reason I could tell. In the meantime, I noticed there was a transcript of a voicemail message left by Comcast indicating that I was at 90% of my data usage for the month.

This I don’t doubt, there was a lot of streaming video going on and a lot of failed attempts to get several large distros from hosting places that I pretty well documented in Twitter rants wasting a whole lot of bandwidth on.

I played around with trying to figure out what was going on with the WiFi calling a bit, but I was pretty busy and only noticed that it worked at other hotspots and other Comcast connections with no issues, just not my home connection. I rebooted everything I own and still no dice.

A couple of days into my 10% remaining bandwidth, I noticed I was getting errors surfing that pages couldn’t be loaded. All of them were framed by a bizarre website I’d never been to constantguard.comcast.net. This is not a service I have, but evidently something that kicks in on your account when you’re nearing the limit.

The first thing I noticed this web service do once it was functioning semi correctly was force a popup on an unrelated website to inform me that my Comcast usage was high. From there on out the only thing it did was cause problems with minor browsing where I’d get the Constantguard error page that it couldn’t load the website I was attempting to go to. It was attempting to pull it up, scan it, and act as the middleman while I neared having to pay Comcast an additional $10 for another 50 gigs of bandwidth.

While a minor inconvenience to web surfing, I quickly put two and two together and figured out that it was this Comcast app that was causing the problem.

To test this theory I connected to a VPN through my Comcast connection and enabled WiFi calling. Worked like a charm, except I didn’t want to be connected through a VPN constantly. I opened up a lot of internet connections (bittorrent, frog, a few SSHs to boxes I own,) and noticed an exceedingly high number of connection drops, likely caused by Constantguard.

My guess is this service kicks in to check for malicious activity on your account when you’ve reached about 90% of what you’ve paid for. It’s probably there to scan and disable botnet drones. What it does for people who rely on a working connection is kill your WiFi calling.

This morning, which should be the beginning of a new service month, I woke up and WiFi calling was working once again, Constantguard appears out of the picture and all is well with the world.

Now if I could just convince developers to stop hosting their multi-gigabyte distros with hosting providers that don’t even support resume for when their three gig distro chokes at 2.8 gigs downloaded, I won’t have to run into this problem again.