upgrade monitored ho9me security system?

A guy is coming to our home this afternoon to get us to upgrade our monitoring station to confirm to Bell 5G (?) network requirements. Said we would need to pay $450 installation fee and have a technician come to our house to install. Want to know from Telus if this is legit as we've never received a notification about such an upgrade from Telus (e.g. an email or letter). Our home phone is (removed number).