I have tried searching for alternatives but am stuck as I do not want to give away personal information about my son on a public website!
He is at Lincoln University, in a room on site.  Each room has an 08700 number for us to contact him on. It's expensive for us and three times the price if he makes outgoing calls!
We use mobiles instead but that's still costly.
Is there an alternative please?

There is an existing thread for Lincoln University Halls here. It goes back to 2004, so you have a look and see if the 0870 number your son has is similar.

If it is, then please continue discussion on that thread so I can remove this one as, at present, it adds nothing.

On the subject of not revealing any private information, I suggest you provide us with, but ** out the last two digits of his 0870 number and the extension number. And say whether the last two digits of 0870 and ext are the same and if not, how they relate.

Thanks Sherbert & Dave, could be helpful. I'll try out the options next week when he's back there. Can we leave this open for a few days then you can remove it?