I once phoned my friend, who was out with her mother who at the time was living with her. I got the sitter. She told me my friend was out but did not identify herself. I thought it was her mum, who responded to questions such as 'how are you'. After several minutes this daft bat decides to tell me she is not my friends mum and we end the call.
I did ask if her child was safe being sat by a woman who answers the phone to a stranger, answers questions that cant be for her and fails for some time to identify herself.