Hi there, You can do, though it needs to be added by our CSC rather than done via the home phone control panel - if you raise a ticket with the request we'll get it added for you. You can raise a ticket to us at http://contactus.plus.net
What exactly is available? The last I knew PN only offered Outgoing Call, Premium Rate and Overseas Call barring and not the flexible Call Barring service offered by BT which, for example, also allows barring of calls to mobile phones.
We can't do the flexible call barring, if we add call barring it'd stop any outgoing calls being made from the line in question. I don't think you can configure it to, say, bar mobile calls but accept landline ones or anything like that.
