Alexa and Echo Connect problem

[DrMark]

Hi folks
I have set up a new Echo connect for my mother who is blind and has difficulties using her landline.  The  Echo connect has its own dedicated BT socket (no splitters) and all lights are solid white.  However Alexa when asked to dial a number sis says its calling the named number, spins green and then stops. Alexa then states that it cannot access the phone at this time.

Any ideas please
Thanks