The number dialed
Is no longer in service.
At any given time organizations (at least the larger ones) are likely have more phone numbers allotted to them than are currently in use. And that makes sense. After all, each time you hire a new employee you don't want to have to contact the phone company and get an additional phone number; likewise, each time an employee retires you don't want to have to contact the phone company and give that phone number back. Instead, organizations are typically allocated blocks of phone numbers; for example, all the numbers between 425-555-0001 and 425-555-9999. The organization is then free to distribute those phone numbers as they see fit.
Of course, that does mean that, at any given time, an organization is likely to have a tidy little collection of phone numbers that aren't being used: if Ken Myer has just retired, and you haven't yet hired a replacement for him, then no one will being using his old phone number. Now, there's nothing wrong with that; there's no law that says you have to use all your allotted phone numbers. Nevertheless, even though no one is using this phone number, it's still a valid number. That means that people (i.e., customers) can still call that number; there just won't be anyone there to answer the call.
Note. Which reminds us of the famous Zen koan: If a phone rings and no one is there to answer it, does the irate customer on the other end, the one who can't get hold of his or her sales representative, make a sound? As it turns out, the answer is "yes," although we're not allowed to reprint the sounds that the irate customer actually makes.
So how do you deal with phone numbers that are perfectly valid numbers, but aren't currently assigned to anyone? Here's how: you configure these numbers as "unassigned numbers."
That was easy, wasn't it?
Oh, good point: why would you want to configure a number as an unassigned number? Well, the main reason for doing so is because you can then configure Microsoft Lync Server 2010 to take the appropriate action if and when someone calls that number. For example, you can configure an announcement file to be played any time an unassigned is called: "We're sorry, but the number you have dialed in not currently in service. Instead, please call 425-555-0001." Alternatively, you can have the call routed to an Exchange Unified Messaging Auto Attendant. The Auto Attendant can then be configured to pose a series of interactive questions ("If you are calling about an existing order, please press 1 ….") that will lead the caller to the promised land. (Or at least to someone who can answer their call.) Is that better than having all those calls go unanswered? Sure seems like it, doesn't it?
Of course, even if we've sold you on the idea, you might be concerned about how you actually go about managing unassigned numbers. But that's no big deal; that's what the CsUnassignedNumber cmdlets (Get-CsUnassignedNumber; New-CsUnassignedNumber; Remove-CsUnassignedNumber; and Set-CsUnassignedNumber) are for. For example, this command creates unassigned numbers for the phone number range 425-555-2100 through 452-555-2200, setting things up so that a call to any one of these numbers is transferred to the Exchange UM Auto Attendant 206-555-1234:
New-CsUnassignedNumber -Identity UNSet2 -NumberRangeStart "+14255552100" -NumberRangeEnd "+14255552200" -ExUmAutoAttendantPhoneNumber "+12065551234"
You might have noticed that this collection of unassigned numbers was given the Identity UNSet2. That makes it very easy to do things like route those numbers to a different Auto Attendant:
Set-CsUnassignedNumber -Identity UNSet2 -ExUmAutoAttendantPhoneNumber "+12065555678"
Or, now that things are looking up and you've hired a bunch of new people, you can easily remove all these numbers from your stockpile of unassigned numbers:
Remove-CsUnassignedNumber -Identity UNSet2
Guess we were right the first time: this was easy.
All in all, are unassigned numbers something good for you to know about? Of course they are. But, then again, what would you expect? After all, here at the Lync Server PowerShell Haiku of the Day, we take things very seriously.