i would like to change the url field in the comments to phone number/general text field. I have changed the langue file to display correct but it does not seem to work - looks like the system is have some check that the input must be a url - could you please assist me to change that so it would except normal text like a phone number?

Hi. This cannot be changed.

ok - can i add a field in the form to include a phone number?

this is one big thing lacking with k2 using it as a directory to contact the author and leave a comment.

You can look at the JED for commenting systems that support this feature (and K2 integration).