Now, I wonder would it have ignited eventually even without the phone.

Cell phones have very powerful RF transmitters.

The fire is a result of RF induction into the big ball of au foil. There is no spark, its from heating alone at the point nearest the cell.

You can hear RF induction yourself, just set your cell near a television thats on. When your cell transmits, say just before ir rings, the rf signal is so powerful it actually moves the speaker coil and you will hear little clicks through your TV.

I repair "gas pumps" and I use my phone around them all the time. Maybe someday I will get bit but I don't think it's likely. By the way, the Dispensers have several RF suppressors in the electronics.

Didnt Mythbusters try this and proved its a load of rubbish?

I'd like to see him try the same experiment but instead of calling that many times, just wait the same length of time and see if it FINALLY combusted because enough vapor had formed.

Petrol isn't going to combust from the amount of heat that could be generated in that ball of foil; it would simply become hot petrol. Seriously, you can boil a pot of petrol without it ever combusting. It's the vapor that combusts.

But that was still a fun experiment. I think I may perform some of my own tests.

HHZ

I should try it next time