interested to find how that works!!
Dont know but someone said something about the built in antenna/receiver on phones 
Still dont understand that though as a £9 cheapy picks up signal better than and all singing and dancing smart phone 
We have tried differing networks and phones including O2 when the family have been down there HTC,IPhones,Samsung's etc and the little cheapo always wins
Same as up here,even loose a 3 signal in the town centre 
The cheap'os will allways win as a simple phone on Signal Strength, as they just have the GSM and PCN dual band, and poss the USA and 2.5/3g to contend with, where as the modern Smart Phone has the added HSDPA, HSDPA+ and 4G on different Bands to sort out, getting Multi Bands to work on a Internal Antenna is bad enough, but the real problem is splitting those Signals for the Receiver's and combining the Transmit Signals back into the same antenna is where all the loss occurs.
I still use my old trusty SE K800i for Voice calls, knocks spots off any Smart Phone in weak area's, for Holidays and going abroad I dig out my old Ericsson T28 with its external Stubby Arial, allways gets weird looks by people but works wonders for making Voice Calls, where everyone else's is no signal