No, calling 911 as your rescue plan is not considered to be an "on-site rescue procedure" which can be "ready for immediate implementation" for the purpose of rescuing a worker from a confined space. Emergency services do not replace the requirement for on-site rescue procedures.
Employers remain solely responsible for ensuring that there are adequate on-site rescue procedures that are ready for immediate implementation in order to effectively remove a worker who has been overcome in a confined space.
Section 11 - Confined Spaces Regulation (O. Reg. 632/05)