So I consulted with a few of my friends who currently are Verizon CDMA customers to ask them how their current device handles being forced to choose between voice and data connections.

Unlike the current GSM AT&T 3G iPhones, which can maintain Voice and Data connections simultaneously, the new Verizon iPhone, based on CDMA technology is forced to use one or the other but NOT both.  This is also the case with any other Verizon CDMA device.

According to my friends, Verizon maintains a voice-priority network.  In other words, lets say you are browsing the web and a phone call comes in - your data connection is terminated.  While talking on the phone, you simply cannot switch to speakerphone, minimize your phone, and use any apps that require network connectivity.  As far as any app is concerned at that point, it's "off the network".  It will be interesting to see how some existing apps misbehave if the iOS developer hasn't correctly implemented the "reachability" classes for network connectivity monitoring.

The bad thing is - this also holds true for tethering.  A few of my friends who use Verizon tethering said that it's a real pain in the ass if they are tethering and/or sharing their connection by way of a hotspot and then a phone call comes in.  When this happens - all network connectivity drops while the voice call is in place, and then the connection resumes once the voice call ends.

In any case - this is a huge flaw that makes this initial launch on Verizon's network less than stellar.  Of course, this restriction mirrors the same behavior of the original iPhone on AT&T's Edge network.  It was only with the introduction of the 3G AT&T iPhones based on the GSM protocol that you could begin using voice and data at the same time.

Moral of the story - if you think you may want to use some apps and use data at the same time as a voice call, or if you don't ever want your data connections to be spontaneously disconnected by a voice call - Verizon iPhone isn't the answer for you..... yet.