A.Ignore both of them and decide what the real problem is.
B.Set up a separate call for each problem.
C.Have them duplicate the problem at the device.
D.Ask a third person and see if the problem is the same thing.

A.Answer the call and talk to your friend at the customer site.
B.Answer the call and tell the friend you will call them later.
C.Let it go to voicemail， call them back between service calls.
D.Let it ring and call the friend back when the customer leaves.