Annoying sound from mobile phone through speakers

[Hamster]

I think we all know about this. When my mobile is about to ring, or sometimes just randomly, i hear buzzing sound signal through my speakers (connected to amp). Is there any known way of stopping this from happening?
Do i need to earth my speakers? If so then what is the easiest way and could it cause any damage to my equipment?

Thanks

 

[Hamster]

Problem is i wouldn't hear my mobile ring from my outdoor shed

 

[Hamster]

You may be right. When i was with 3 this didn't happen. Only with O2 for me too. Do you think they'll let me out of my contract 14 month early?