Any recommendations for Prepaid 3G service in Montreal?

I bought my father one of these 3G/4G mobile routers so that he could connect his iPad to the internet via prepaid SIM cards when he travels. This way he doesn’t have to worry about telling his regular phone service provider to switch on/off his data roaming or futz around with his iPad settings. He just leaves data roaming OFF all the time.

He’s heading to Montreal next month for a conference. Can you recommend any pre-paid 3G data service in that city? Ideally, he could find it at the airport or any newsstand. Then he slips it into his mobile router and can pretty much forget about for the week that he’s there.

Here is the mobile router I got for him. I use a similar one from another brand that I use to travel around Asia.