What is Internal Enterprise Extension?

Last week at Microsoft Tech·Ed Europe 2009 in Berlin several attendees came to the UC Booth and asked about the usage of the Internal Enterprise Extension flag in a OCS 2007 R2 normalization rule. Since it seems to be an interesting topic I wanted to write about it.

The official documentation on the topic is located here. The usage of the flag has to do with the off-hook dialing experience when using OCPE powered devices. The interesting sentence is “If the first digit dialed by a user matches the external access prefix, the device (such as Communicator Phone Edition) ignores the digit and does not use rules that are tagged as InternalExtension”.

Let’s explain it with an example: Consider a location profile containing the following normalization rules, the External Access Prefix set to 9 and the Optimize for Device Dialing set to True.

Rule	Pattern	Translation	Internal Enterprise Extension	Quick Dial
Ext1	^(13\d{2})$	1399	True	True
Ext2	^(13\d{2})$	1355	False	True

On the OCPE you sign in with a user assigned the location profile above. The user enters off-hook dialing mode by pressing the loudspeaker icon or lifting the handset. The table below shows the results of dialing different numbers.

Entered	Normalized to	Using Rule
1322	1399	Ext1
91322	1355	Ext2

In the first case the user didn’t use the external access prefix and therefore the normalization rule Ext1 was used. In the second case the user used the external access prefix, but since Ext1 has Internal Enterprise Extension set to True that rule was not used by the device and it used Ext2 instead.