Google's GrandCentral telephony service was reported back to functioning normally Monday following an outage Sunday for a few hours.

The highly acclaimed service, which consolidates a user's phone numbers into one free lifelong number and voicemail, went dead Sunday morning for a few hours.

"We had a power issue at our current Colo(rado) facility and it knocked us off line for a few hours," wrote GrandCentral cofounder and CEO Craig Walker in his blog. "I did want to let you know that we were able to restore the service by noon today (Sunday) and are working extremely diligently to make sure this won't occur in the future."

Word of the GrandCentral service outage first surfaced in a flurry of complaints on Twitter by users who grumbled that they couldn't receive their calls. The outage appeared to be the first for the service, which Google acquired in June of 2007.

Some iPhone owners have had trouble using the service, which asks users to press a button on their keypad to carry out the various GrandCentral functions ranging from accepting calls to sending calls to voice mail. iPhone users generally have to perform a complicated series of hand maneuvers including sliding the bar on the screen to pressing a series of spaces on the keypad to activate GrandCentral.

"Try doing that when you're driving," wrote one iPhone user, who said he loves his phone and GrandCentral, but not their inability to work well together. "Both the iPhone and GrandCentral work great independent of each other, but together, their features make it extremely annoying to use."

GrandCentral has built a base of loyal users who hail the concept of its "one phone number for all your phones, for life." The service seems tailor made for an increasingly mobile society and work force, which moves about the country. Users can program the service to shunt calls to different numbers, voice mail and even email addresses. The service works well with both wireline and mobile devices.