Convergence is a solution that aims to increase business productivity by allowing employees to answer incoming calls on their fixed phones, even when they are not in the office. Convergence is about improving reachability by combining fixed and mobile subscriptions on a single device. So, a single number and a single voicemail box concern both fixed and mobile phones. The mobile phone will benefit from the same technical specifications as the mobile phone (e.g. call forwarding). In short, it amounts to merging fixed and mobile.