Google Fiber launched more than three years ago with gigabit Internet and TV, but not phone service.

Now, Google might finally be adding a VoIP phone component in order to duplicate the "triple-play" bundle offered by many ISPs. The Washington Post reported today that Google is sending invitations to try a new home phone service to members of its "Fiber Trusted Tester" program.

"Our latest offering is Google Fiber Phone, which gives you the chance to add home phone service to your current Fiber service plan," the invitation said. (See the full invitation here.)

The Trusted Tester program tries out new features, services, and devices before they're rolled out to other Fiber customers. Testers give Google feedback, helping the company decide whether to make the new product available to all Fiber customers.

Adding Fiber Phone requires a service visit from a Google Fiber employee and installation of a new piece of equipment. It sounds like Fiber Phone will wrap in some of the features of the Web- and smartphone-based service Google Voice.

Fiber Phone will feature "a phone number that lives in the cloud," Google said. "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." There will also be voicemail transcription, spam filtering, call screening, and do-not-disturb. Customers can get a new number or transfer an existing landline or cell phone number to Fiber Phone.

Google considered offering phone service when it first launched Fiber, but the company decided not to go through with it because phone service faces additional regulations.

"Google would’ve had to devote a fair amount of work on billing systems to support phone services because of the different state tax calculations involved in Kansas and Missouri," the Kansas City Business Journal reported at the time of the Kansas City launch. There are also federal regulations for VoIP service, including 911 requirements.

Google Fiber is available today in Kansas City, Kansas and Missouri; Provo, Utah; and Austin, Texas. There are tentative plans to expand to another 17 metro areas.

We contacted Google this afternoon to get more information on its Fiber Phone plans, but the company said it would not comment on "speculation."

Google also has its own cellular service known as Project Fi, which runs on top of the Sprint and T-Mobile USA networks.