You can expect microwave to be a lot more reliable than your typical leased T1, and that's one of the main reasons to go with it. In wireless parlance, we refer to uptime as "link availability". The published uptime figure for leased lines is 99.985%, meaning that you can anticipate being out of service for .015% of the year. It sounds like splitting hairs, but you'll see that it's not.

Consider where free space optics (e.g., laser / infrared) is often quoted in the 99% range for reliability, particularly on lengthy paths. Ninety-nine percent sounds great on the surface, but that one percent of downtime translates to more than three and a half days in a single year; a hefty blow to cost and productivity.

That being said, a microwave radio connection should give you at lease "four-nines, meaning 99.99%, and many times it will give you five-nines. This means that the microwave link is not expected to go down at all, except from natural component death and in that case our mean time between failure (MTBF) ranges 55,000 hours. This number is made more meaningful by the fact that our MTBF rates are based on real world numbers and not lab simulations.

Fiber and licensed microwave are the two most reliable mediums, bar none. Combine the two for "mixed-media backup" and you have the cadillac solution - more effective and less costly than a second fiber route. Actually, if you compare uptime for fiber and microwave over a ten year period, you'd find that microwave has greater cumulative uptime. That's because microwave downtime periods can be limited, where many breaks in the public fiber networks have been reported to last for days.

On the other hand, we fully grant the concession that the utmost in reliability is where you own and control the land between your buildings and can connect them with your own dedicated fiber. Microwave can bring you close to that ideal, only without the huge hit on your budget.