Telus WCDMA frequencies issue question

I call Telus requested the WCDMA/HSPA frequency they are using but told are 800 mhz and 1900 Mhz. However, I search online found that the Telus/Bell WCDMA/HSPA frequencies are 850/1900 MHZ. I wonder which one is correct?

Another thing, if I buy a smart phone with WCDMA/HSPA 850/1900/2100 Mhz frequency, will it works on Telus even if the Telus customer service told me it's 800/1900 mhz. What about a WCDMA 3G phone with 900/1900/2100 mhz, will still be compatible?

I am a little confuse here on the 50mhz differences compatibility here.

...will highly appreciate if someone could help...