Caller: The line seems to be discontinued

This is the phone number of a very dear (elderly) friend (since the 1950's) of my (also elderly) mum's and they regularly chatted. My mum lives in the UK so there is no other way for them to communicate. For the last few weeks, she hasn't managed to get through as she gets a message saying that this number is discontinued or not connected and she is very concerned that perhaps her friend has died and no-one has told her. Is there any way to get this message to the other people listed on this number so that they can email me and let me know what's happening? my email is lizzyp1962 @ gmail.com