Call forwarding

Yes it does. It doesn't cost anything, assuming you're forwarding to a number which is included in your package (i.e. a standard UK landline or mobile number).

threepennys  There is a helpful document: https://help.smarty.co.uk/en/articles/1463317-setting-up-call-forwarding

As far as I'm aware, there is no charge as it involves calls to UK land or mobile which is included in the plan.

(Anyone else please feel free to advise otherwise if I'm wrong!)