You can't trust any of this when it comes to mobile networks, they control the domain and have to play by their rules.

Example? I used to work at a company that made femtocells, basically small 3g base stations. All 2 way radios are a co-operative medium, i.e. shouting 'fire' in a crowded room raises the noise floor for everybody so they all need to shout.

We had hundreds of handsets for testing so knew when a particular model/brand/firmware version wasn't working to spec. We'd shoot an email to the manufacturer to get it sorted. Most were fine, but the one that never responded? A certain fruit related company.