We have Spectrum cell service as well and have used it on the island and to call to the island. There are some taxes added to the rates but it is still only around 9 cents per minute and works well. In March I used it a few times to call home and to also make local SXM calls but if you have access to wi-fi, you can use that and avoid any charges. One just has to remember to change to and from airplane mode. You also have to make sure you have international calling activated on your Spectrum phone/account.

I also have a SXM cell and still use it some as I have time/credit on it and also my Chippie card. It was bought prior to the Spectrum cell service.

I have no idea if Spectrum is available in Canada as the poster that started the post is from Canada.

WhatsApp is a good alternative also.