It should have been explained to you, but also important to read the terms and conditio s of contracts/agreements!! (I know, no one does, and I never did until I started working at my job).
As per the Bell Mobility Terms...
4. Does Bell collect, use or disclose my credit information?
Does Bell collect, use or disclose my credit information? If you are a Postpaid Customer, then by accepting this Agreement you consent to our conducting credit checks on you, and our use and collection of your credit and payment history from other Bell companies, credit reporting agencies or other credit grantors to assess your creditworthiness, update your information, activate your ordered services, or assist in collection efforts, all from time to time. You also consent to our disclosure of your credit and payment history with other Bell companies, to credit reporting agencies and credit grantors to assist with assessing your creditworthiness, and to collection agencies to assist with the collection of monies owed, all from time to time. Prepaid Services are available without a credit check.
https://www.bell.ca/Bell_Mobility_Terms_of_service
From what thay tells me, is that they can do credit checks anytime.
I am not familiar with other companies and what they do, I have not dug into everyones terms and services (and for the ones I have and brought something up from it, the person I was speaking with disagreed with it anyways and said it wasnt true).