Huawei Ascend P6 — Losing connection during phone calls

Hi I was hoping someone could help me,my wife recently signed up for 24 month contract but her phone keeps dropping calls,we got a new sim plus got the phone exchanged but it still happens is there a setting somewhere we need to configure,i work in IT but this has me totally confused i've tried putting both phones on loud speaker just in case she was touching off something but its still the same.We used an old sony ericsson and it worked fine no problems at all,i cant believe there is a problem with 2 new phones,any ideas would be appreciated

— modified on Nov 4, 2013, 3:40:37 PM