Mobile phone/speaker interference

[ihoss.com]

You all know what I'm talking about. Its that sound your speakers make just before you receive an sms or a phonecall. Before you read the rest of the message, stand by with your tin-foil hats.

I tried googling this, but I can't find what actually causes it. Is it the radiowaves carrying the message? Then we should hear it all the time, because those radiowaves spread evenly around a tower, so as long as the tower is sending a message to any phone my speakers should pick it up.

I also tried to record the sound it makes. If you have a headset, then put the headset cable into the speaker cable, coil the wire around the phone and send a message.

I recorded the sound because if it is the radiowaves, then it should be possible to get the message from the sound! It's probably not possible, but it would be cool to look into it/find out if anyone has.

So, anyone know anything about this phenomenon?

[Subway]

From what I know your cell phone sends out short burst of stronger signals in some cases. I see the same effect you describe on one of my speaker sets. Thing is, sometimes it happens when I don't get a call SMS etc., so it's not directly related to that. My guess is that to get the optimal reception without having to send at full power, the phone does those short burst to find the optimal level of outgoing signals.

Fredi

[el-Ignoramus]

it's a GSM thing, the phone have to acknowledge it's presence on the Network, thus it sends a signal telling the nearest tower(s) "I'm here and I'm available", same thing when you get the call routed to you, the tower is looking for you

[asheep_uk]

The other thing to remember is that not all speakers are effected. I have monitor speakers which do not pick up the interference.