Hi Harry
We have just arrived back from Spain.
Apparently at the moment you have to initially connect with Telefonica - the number in Spain to ring is 1004. Noone in Spain appears to know a number you can dial from the UK, however I would imagine Telefonica must have a web site. (hopefully with an english translation)
Our agents have said that as all the telephone points are in, it should be fairly straight forward, but you just need a little patience.
Once you have connected with Telefonica, if you are living out there full time & want a broadband connection, mobile phone package etc you can get better deals with companies such as Europa.
UK telephones we are told are not compatible, but not sure that anyione we spoke to has actually tried one out - they do seem really cheap to buy though.
Kind Regards David & Sue