Yes — Colorado requires a telephone within 20 feet of the pool, capable of dialing emergency services (ISPSC 2021 §412.2).
Colorado has adopted ISPSC 2021 §412.2, requiring a telephone within 20 feet of the pool that is capable of dialing emergency services.
Citation: ISPSC 2021 §412.2
The 20-foot radius is measured from the pool's edge, so plan phone placement early when designing or retrofitting a pool deck. A weatherproof, direct-dial cellular unit mounted on a nearby wall or post is a common way to meet this distance requirement.
SouthEast Telephone installs and monitors cellular emergency pool phones nationwide and can help you meet Colorado's requirements.