On-screen activation ONLY applies for prepaid HSPA activations. If you wish to have LTE access, you MUST activate a postpaid plan, through a store or customer service, with an LTE MicroSIM card. If you want prepaid, you will only get HSPA speeds...in these cases, a standard "pre-provisioned" HSPA SIM will work. These SIMs specifically say "pre-provisioned" on them.
For those that say "Telus still works", it'll be exactly the same as Bell. Prepaid services will NOT be provisioned for access on LTE.