When you send a text to someone as I understand it they are transmitted to the other persons phone via a satellite. When the other phone is off they don't recieve this till later when it is switched on. Where is this text in the mean time? This may seem incredibly stupid but I could't figure it out.

I can readily understand why the strength of the signal received by my mobile phone should vary while I am travelling my train.

What I do not understand is why the same thing happens when I am at home. Why does my signal vary so much.

Jonathan Wallace, Newcastle upon Tyne, UK

When I was filling my car in a petrol station the other day the other day I saw a sign requesting that mobile phones be switched off. When I asked the cashier the reason for th request he said that they could cause the petrol vapour to ignite spontaneously.  I know that mobile phones emit radiation but I fail to see how they could ignite petrol.  Is this an urban myth or is it true, and if so, where did the incident that created this situation occur?

Situation is....Husband locks himself out of his car. His wireless keyfob is on the drivers seat. He uses his mobile phone to call his wife's mobile phone.

She puts her keyfob (to the same car) against her mobile phone. Husband puts mobile phone near drivers window. She presses keyfob and the car doors open.

When I was first told this I dismissed it out of hand as another internet hoax, but I have since seen it demonstrated.

I have some understanding about wireless communication but I cannot envisage the mechanism by which this happens. Car keyfobs operate on 430 MHZ, and mobile phones on 900 MHz (I believe).

How can any effect from a wireless keyfob travel with the mobile phone signal across the cellphone networks and emerge as a useful signal at the other end?