CPS (Carrier Pre-Select) is a service from BT (a form of provisioning at the BT exchange) which routes your calls over pre chosen networks (BT, Opal, C&W and Thus). Choosing Z1 Telecom as your communications provider will ensure that all your calls are billed at the agreed rate. You will not receive a bill from BT for any calls or lines whatsoever. With the Z1 Calls & Lines packages you receive one bill showing line rental and itemised calls rather than two independent, and in some cases very complicated, bills. Your telephone lines, numbers or services will not change. For example, BT Wholesale (now known as BT Openreach) will be responsible for your lines, your telephone numbers will stay the same and you will still get the 'Select' services' and be able to divert calls etc. We will continue to support those services and will itemise these charges on your bill.