using a mobile phone as a signal strength meter

[phred01]

Hi all
I have used a android phone to measure signal strength using Android apps. Do know that the radio methodology uses digital spread spectrum so using a spectrum analyser is futile However I can only measure a specific carrier as embedded in the sim card. Say a Telstra will only test Telstra towers. Is there away to make the phone pretend as universal unit that enables the signal strength apps to measure any towers signal