We have two Nokia phones one on CDMA and one on XT. Both keyboards flash at about every 5 seconds, and just about in sync. I have always assumed this is a function of the network polling rate to keep the mobile in touch with the local cell site.

I also have a CFL's fitted through the house. One of them joins in with both mobiles and all three flash more or less in sync. Its been going on as long I can recall probably from the time I fitted the CFL's.

OK you are going to say its the Mobiles response setting off the CFL. No, both phones can be off and the CFL keeps going. Switch the phones back on and they are all in sync again.

If I drop the circuit breaker for the lights and the CFL stops, Change the CFL in the socket and the new CFL gets in sync. So its that light one socket. From what I can tell no others do it.

My assumption is the power lines are picking up the poll signal from the cell site and feeding the pulse into the house. That's strange though because our signal for CDMA and XT is poor in the house and our nearest mast is well over 1/2Km away and 160mtrs below us, and the other is 3/4Km away and behind a hill.

So the questions for now are

1) are the Nokia keyboard flashes a function of polling rate?
2) do the cell sites poll the mobiles, or the mobiles just ping out ?
3) Whatever it is what rate is it ?
4) is XT and CDMA polling in sync?