With call waiting, if a user is busy on a call they can chose to have another call wait for them until they become free. The user will be made aware that a call that is waiting for them by a call waiting tone and, by using Phone Manager, they will receive additional information to assist them to decide which conversation they wish to continue with.
Avaya phone systems provide various options. The user may:

Telefonix Voice & Data
3 Albany Park, Camberley,
Surrey GU167QR, England
Tel: +44 01252 333 888
Company Reg: 04351046