Cablevision Systems plans to announce on Monday the start of a low-cost mobile phone service that will use Wi-Fi for connectivity rather than standard cellular networks, the first such service to be introduced by a cable operator.

Called Freewheel, the service will offer unlimited data, talking and texting worldwide for $29.95 a month, or $9.95 a month for Cablevision’s Optimum Online customers — a steep discount compared with standard offerings from traditional cellular carriers. Freewheel customers initially must use a specific Motorola Moto G smartphone, which is being sold for $99.95. The service goes on sale next month, and no annual contract is required.

The service will not offer a seamless connection for people on the go. Freewheel only works when the device is connected to Wi-Fi. (One exception is for emergency calls, which will be placed regardless of whether Wi-Fi is available.)

Cablevision has spent the last eight years building out its Wi-Fi network, which now offers more than 1.1 million hot spots for both indoor and outdoor access in the New York metro region.