My house has a metal roof and I cannot receive cell calls inside so the past three years I have been living here I have set my iPhone to forward calls to the house number. The past few weeks when I have call forwarding on the calls will not ring on my house phone and they go straight to voicemail. When I turn off call forwarding I receive calls on my iPhone 6s fine? I have tried *73, resetting the network, turning the phone off, etc nothing fixes it. Not sure what else to try?