I have service with Airvoice Wireless. I will be vacationing in Canada and was informed by an Airvoice representative that Airvoice does not provide calling/texting from Canada to the US. I am aware there are apps that will allow me to text/call via wifi, but it seems as if I only will be able to text/call other people who are using the same app (ex: WhatsApp, Tango, etc.). Also there are apps that will give me a new phone number connected with that app. Are there any apps where I will be able to call/text using my existing phone number and will work with all my contacts even if they are not using the same app? I am fine using an app through data or wifi.