Help HELP!!!!! Its got me puzzled

[Jelly22]

Hi

I have recently purchased a HTC desire s and its been great. My problem is every time i ring my partner i get this constent buzzing. it only happens when i ring him or he rings me. it doesnt happen with any other telephone numbers........Can any1 help.

Thanks

 

[notebook]

Have you thought that his phone could be making the noise?