Want to see what the future of T-Mobile’s 4G HSPA+ network looks like? Just head north and check out Canada’s Bell Mobility which is launching the first HSPA+ device that supports maximum download speeds of 42 Mbps.

T-Mobile’s current 4G HSPA+ network tops off at 21 Mbps, but the carrier already announced they would double those speeds in 2011. While we don’t know what types of devices T-Mobile will offer, we can see that Bell Mobility is selling a Novatel Wireless USB modem that offers real world speeds of 7-14 Mbps.

If you remember the Verizon 4G LTE chart from yesterday, they were advertising their network was the most advanced and could do real world speeds of 5-12 Mbps. I’m sure Verizon will continue to improve their LTE network and offer faster speeds, but the point is that other technologies like HSPA+ and WiMAX can also scale up in the near future and will offer comparable speeds.

So far T-Mobile has yet to charge customers any additional fees for using a 4G handset, but Bell Mobility will attach a monthly $10 fee for access to the 42 Mbps speeds. Sprint also charges a $10 4G WiMAX fee and Verizon is exploring the idea of speed-based pricing, so don’t be surprised to see T-Mobile eventually do the same thing.