The CapTel 2400i/840i/880i requires telephone service to work. The telephone service can be:
- Standard analog service
- DSL (Digital Subscriber Line)
- Digital Cable phone service
- VoIP (Voice Over Internet Protocol) service
- Fiber Optics phone service
The CapTel 2400i/840i/880i does NOT work with digital PBX (Private Branch Exchange) phone systems found in some business settings, residential facilities, hospitals, and hotels unless an analog port is available in the PBX network.