Maintaining a call with no service

Have you ever noticed that when you’re in an area with no cell phone service, you can’t make a call, but when you leave that area and then make the call, you can go back into that area and the call will stay connected? I’m not talking about big no-service areas, but small areas of no coverage within larger areas that should have coverage.

For example, there is no cell phone service anywhere in the building where I work, except by the windows. If you stand by the window, you get a signal and can make calls, but if you move away from the windows, service drops and you can’t make a call. This happens 100% of the time. However, if you make a call while you’re standing by the window, the call will continue throughout the building (very clearly), no matter where you go. If you end the call, after a few seconds your signal will drop down to nothing and you can’t make calls anymore.

That’s just one example. I’ve noticed this happening everywhere. The last house I lived in was the same way. There was one room that didn’t get service, but if you started a call somewhere else, you could continue the call in that room with no problems.

Why is that? If the signal is strong enough to continue a call, why isn’t it strong enough to place a call? I’m hoping for an actual scientific answer, if there is one.

How long can you continue the call? Service in any given location isn’t constant: Poor service means that there’s a high chance of the call being dropped. If the chance of dropping is high enough, the phone system might decide that there’s no point in even trying. But if you’re already on a call, it is going to try to maintain it, if it can. Until, of course, the clouds shift, or the interference increases, or whatever, and it can’t maintain the connection any more.