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Can you hear me now?

July 30th, 2007

It’s funny how the bleeding edge folks often miss the train. For instance, Jenn and I have spent a lot of time working on VOIP networks. Jenn single-handedly ran the NOC for a small VOIP provider and I wrote a software package to do large-scale wiretapping of VOIP networks for a CLEC. In spite of all this, we had never used Skype until last night!

In researching our communications options we decided that we wanted internet and voice communication that would work pretty much anywhere and of course we want it as cheaply as possible.

Cell coverage is pretty good with relatively high speed and low latency in the data packages. However, you have to be near a cell tower and preferably near one of the newer towers for high speed internet service.

Satellite internet works pretty much anywhere, but with significantly higher latency than cellular internet service. We can add in VOIP for a very low cost and piggy back our voice communications on top of our data communications much like a cellular network in reverse.

The variables we have to deal with are cost, coverage and quality of service. So far, I believe cellular data + voice is roughly twice the cost of satellite data + voice. On the east coast, cellular coverage is pretty good, but still spotty in a lot of remote locations. Out west it is considerably worse. Latency and setup time on a satellite connection are the two biggest flaws. You can’t really use satellite internet without spending 15-30 minutes setting up unless you drop 5k or so on a high end installation.

As our plan is to only drive 50-100 miles at a time and stay for a week or three at each location, the setup and lack of mobility isn’t too much of an issue. We’ve already sworn off internet gaming for the short term, so the biggest latency issue is likely to be with VOIP.

Last night, I decided to test out Skype. In order to simulate satellite latency, I routed a call via an overly complicated method. Caller was a laptop connected via ‘blackberry modem mode’. I’m not sure what data speed this really connects at, but the virtual serial port gets sets to 115.2kb, so that’s about 1/3 of satellite upstream capabilities. The party being called was using another VOIP phone on a separate network; as such, routing of the call was something like this:

Computer->USB->Cellular->Internet->PSTN->Internet->VOIP box.

Overall, call quality was very good. We experienced up to about 2 seconds latency at the peak and maybe .75 seconds average. Voice quality was excellent except for a few streaming/encoding glitches coming from the non-skype telephone. Our overall impression was that we could easily hold a conversation across a pretty low-bandwidth, high latency network.

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