Cheap Gsm Or Landline Package For Companies And Their Staff

Help!!! Please who knows about a GSM or Landline package that is specifically designed for companies and her staff to reduce their phonebills which definitely should be cheaper than using any of MTN, Glo, Celtel, or Starcomms line in their classic packages. My company seeks to reduce her staffs' phonebills or enter a new package for the entire staff that shall readily accommodate the present amount voted by the company for each staff's phonecalls. Presently, each staff is given a monthly subvention for his/her phone calls. Staff are presently complaining that the amount, which though is reasonable, does not cover ALL of their phone bills and Management is looking for a new package that is cheaper which can accommodate all staff.  Please help!