Most live games and online sites will NOT allow this.
Hellmuth was coaching Shulman at the WSOP
Main Event but he couldn't come down to discuss the hands with him.
It is one of the reasons phones, pages text messages etc are not allowed at the table
On many occasion I have been on the phone or IM'ing with buddies playing online BUT it is for trash talking, bragging and general conversation. We never discuss our hands or opponents hands.