How do they communicate?

[Sandra Collins]

No: HPFGUIDX 136039

Apologies if this has already been done,  but seeing as the WW 
has no idea about electricity and many things which we take for 
granted, how do they get in touch with each other if they just fancy 
a chat? I remember Mr Weasley having trouble with using a 
phone at the start of book 2 (I think) so I'm assuming that these 
people don't always have to apparate in each other's rooms 
when they want to say hello? It's an area which I might have 
missed. I was replying to a 2 Way Mirror topic, and it got me 
wondering. Either the WW is full of multi-way mirrors, or there's 
some other means that might have been mentioned.

Sandra