The university has inserted a number of mobile phone Sim cards into its Cellclear private branch exchange box. The PBX routes calls from desktop landlines via the Sims to make it cheaper to call mobile phones using bundled minutes supplied by a mobile operator.
When bundled minutes from one Sim run out in a Cellclear box, calls are transferred through an alternative Sim which still has cheap minutes available.
Before installing the Cellclear product, the university was paying up to 16p a minute for its mobile calls. It is now paying roughly 5p a minute to its mobile operator and another 2p a minute to Cellclear.
The Communications Management Association estimated that up to 80% of a company's call charges can be to mobile devices.