Whoever put that wording on the bag appears to have been completely confused when they did it.
It should say "
Calls cost Xp per minute [Service Charge] plus your phone providers Access Charge."
... where the Service Charge "X" can be looked up at
http://checkit.uboss.com/The Access Charge is up to 12p per minute from landlines or up to 45p per minute from mobiles.
It would be interesting to compare the current text with whatever was previously printed on the bags a year or two ago.
My guess is that it used to say "
Calls cost 5.5p per minute plus a Xp connection fee from a BT landline. Other providers and mobiles may charge more", quoting BT's non-inclusive call price from many years ago.
The new wording is probably a badly edited change made by someone who had no idea what they were doing.