Hope someone has the answer to this as its driving me mad.
I have the following
1st Mobile: Virgin Mobile
2nd Mobile: GiffGaff
Making and receiving calls on any phone in the UK is fine. When I call abroad on the Landline or Virgin mobile (tried 6 different people) they cannot hear me but I can hear them. When the same people ring me on both Virgin numbers they can hear me and I can hear them. Incoming and outgoing calls abroad on GiffGaff mobile is fine.