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My understanding of how the Blackberry data service works is not sufficiently clear.

First some observations.

When on a phone call, email data does not work.

However, I saw a bizarre issue when I was on voice mail, that email continued to stream in. I had 97 messages after being off for the weekend so the messages just kept coming in. That seemed odd. But I wondered if voice mail is a special case of a phone call.

I have found, that while on long conference calls that I can break out to my GMail client and read my email there. It appears that data continues to work.

The Web browser does not work while on a call. However Opera browser seems to continue working.

From this I would infer that the data channel that BB email works (push mail) is shared with the voice channel.

I had read somewhere that I can no longer find (some crazy search last year) that the data flow of TCP data flows across the carrier network, to the RIM data center, which then gets back out to the public internet network.

Thus there are many bottlenecks that may come up.

To make this fun, I have a T-Mobile BB (alas, no 3G) that uses WiFi when at home, but sets up an interesting set of services, called UMA, which when you look at the WiFi diagnostic screen on the phone, it describes a number of services that I am still trying to make heads or tails of.

First off, am I totally off base here, or has anyone found a really nice description of how the data service actually works.

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up vote 1 down vote accepted

It depends on the phone (which is especially obvious with BB Connect devices) and the radio internally (and also how well it's been programmed). Some phones support having both a voice and a data channel open, some don't. Most commonly, you can't have both GPRS and voice channels open and more commonly phones support having 3g and voice channels open but this isn't a hard and fast rule. It's also possible from the use-cases you've given that some applications are actually disconnecting their data channel if they detect a voice call in progress.

Basically, it is as you thought, dependent on if the data channel is using the same radio as the voice channel, but with some added complications.

As for the backend, my experience is with BB connect and that uses the phone data connection (so GPRS, 3g, HDPSA) and connects to a RIM server gateway. It's this that then uses your phones registration data to work out which BB server to send to (or the BIS servers if you aren't on an enterprise server) using routing information the phone keeps stored. On BB Connect at least, it doesn't use the voice channel directly apart from as stated above when they can interfere.

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