Has the phone worked on the Telus network previously? If yes, then the usual recommended troubleshooting is here: https://www.telus.com/en/bc/support/article/cant-make-or-receive-voice-calls. One additional troubleshooting step if the phone previously worked with Telus would be to remove and re-insert the SIM card.
If you have a new phone and it's never worked with Telus, please post the make and model of the device. There is a possibility it may not be compatible.