cheap overseas calls from a landline

Curlietop

I used to use Rebtel to call someone in the USA, but I now need urgently to find another provider as the Rebtel number no longer works. I have found several options and wondered which would be the most reliable:  

www.call18866.co.uk

www.freecallstousa.co.uk

www.toolani.com

call2call.co.uk

There are probably more out there, maybe better ones, but these are what I have found.
I can't use anything that requires an app as my friend does not have a smartphone or a computer.

Many thanks in advance

viva1

https://www.zipcall.com/international-calls/

mobileron

just look or voip call suppliers or use skype