I am travelling down to the States for a week and getting the unlimited 10 day sms package. Will my friend who is in the states and on a Verizon phone plan be able to send me sms messages without getting charged? Or will they because I am still using a Canadian phone number?
They will have to verify with their own provider. With the add-on you will not receive any charges. However, you are still considered as having a Canadian number and your friend will be charged accordingly.