I am not sure about this. To have a volunteerfrom Age UK ring me and have a general chat about whatever I want to talk about this week is one thing. There is an element of freedom and give or take and a chance of a relation growing up between volunteer and the isolated person
To know that someone is paid to ring you is very different. Can you guarantee that the same person will ring every week, or will it be whoeever is available? With these schemes, getting that rapport between the two people at each end of the phone is very important. If the person is going to change from week to week, I do not think it would work.