Pushing ahead on trials that emerged in January, Google Fiber has introduced Fiber Phone, a $10 per month optional add-on that will become available to customers on its basic Internet service, 1-Gig standalone broadband offering, and subs who take its gigabit/pay-TV bundle.

Though Fiber Phone will be available as part of a double-play bundle by pairing it with a high-speed Internet service, the new option will give Google Fiber a way to offer triple-play packages that have long been available from its MSO and telco competitors.

Fiber Phone features unlimited local and nationwide calling as well as the same rates Google Voice offers for international calls. Using some of the same tech that powers Google Voice, Fiber Phone will let customers port their old phone number or pick a new one, and supports features such as call waiting, caller ID and a service that transcribes voice mails, John Shriver-Blake, product manager at Google Fiber, explained in this blog post.

As a cloud-based service, Fiber Phone is supported on a wide range of phones, tablets and laptops. “It can ring your landline when you’re home, or your mobile device when you’re on-the-go,” Shriver-Blake said.

He said Fiber Phone will be offered in a “few areas to start,” but the plan is to launch the service in all Google Fiber cities.

Google Fiber has not announced which markets will get it in the early going. But candidates include all the markets where Google Fiber has launched service -- Kansas City, Kan.; Kansas City, Mo.; Provo, Utah;  and Austin, Texas.

Google Fiber has also committed to deploy in Atlanta; Salt Lake City; San  Antonio; Nashville, Tenn.; and Charlotte and Raleigh-Durham, N.C. It’s considering expansions in Chicago; Portland, Ore.; Los Angeles, San Jose, Irvine and San Diego, Calif.; Phoenix; Oklahoma City; Louisville, Ky.; and Jacksonville and Tampa, Fla.

Google Fiber appears to be flirting with a triple-play offering as it gears up to test a residential voice service called Google Fiber Phone.

Google Fiber has sent invitations for the trial to some of its subscribers, according to The Washington Post, which has also posted an image of the invitation, which Google had hoped to keep confidential.

According to that invitation, Google is offering access to the Google Fiber Phone trial via its Fiber Trusted Tester program, which gives customers “early access to confidential products and features.”

Sharing apparent similarities with the Google Voice product, Google Fiber Phone provides a “phone number that lives in the cloud. With Fiber Phone, you can use the right phone for your needs, whether it’s your mobile device on the go or your landline at home.”

The service being trialed also supports features such as voice mail transcribing, call screening, do-not-disturb settings, and the option for testers to receive a new number or transfer one from an existing landline or cell number.

Google Fiber currently sells a 1 Gbps standalone service for $70, the option to bundle in a pay TV service, as well as a free "basic" Internet service that is limited to 5 Mbps down by 1 Mbps up for customers who agree to pay a one-time construction fee. Adding a residential voice product would complete a triple-play bundle for  Google Fiber. Separately, Google has launched Project Fi, a mobile voice service that starts at $20 per month that runs on WiFi hot spots as well as Sprint’s and T-Mobile 4G LTE cellular networks.

Google declined to comment about the Google Fiber Phone trial. It’s not clear if Google Fiber is testing the voice service in Kansas City, its first market, or if it has extended it to customers in Provo, Utah; and Austin, Texas. Google Fiber also has buildouts underway in Salt Lake City, San Antonio, Nashville, Atlanta, Raleigh-Durham and Charlotte. It’s also exploring deployments in several markets, including Chicago; Los Angeles; Portland, Ore.; San Jose, Irvine and San Diego, Calif.; Phoenix, Ariz.; Oklahoma City; Louisville, Ky.; and Jacksonville and Tampa, Fla.

In October 2015, Bernstein Research  estimatedthat Google Fiber’s network passed about 427,000 homes and 96,000 business locations, primarily in Kansas City and Provo, Utah, and that it had signed up as many as 120,000 paid subs.