Have you recently changed your plan to a “unlimited-Canada wide” plan? Did you roam recently?

To see the reasons of the charge, you can download the PDF bill in selfserve, check the page 3 and 4 of it. The reason should be there. There is also a possibility of international long distance call.

@Adamdf101 The ‘airtime’ charge you see is for using Call Forwarding on a pay-per-use basis. You detailed bill describes the days it was used. The charge is $0.50 for each use. If this something you are planning on using frequently you may want to consider the monthly add-on as it is far more economical. You can add and remove as often as you wish.  I hope this helps!