How do controllers know about remote extensions

[ricvil]

Hi,

Being new to the Mitel world, I would like to understand how controllers in a cluster learn about extensions on remote nodes.  Case in point.  I have two 3300 controllers (release 6 SP3) in a cluster.  They both clearly display the SDS Data Sharing column as "NO" when viewing the network elements form.  That clearly tells me they are not synchronizing their databases and as far as I can remember never have in the past.  Nevertheless every time we add an extension in either of the controllers, people in the remote controller can immediately dial the new extension. 

So how does controller A learn about extensions of controller B if data sharing is not enabled?

Thanks.

[NEPhoneGuy]

I'd venture to guess they don't know per se that a new extension has been created but that the new extension can be reached by an existing dial plan and thus the call goes through.

[johnp]

Might be using ip trunking such that the leading digit for each site is in ars.

[ricvil]

There is an IP Trunk between the two but the only entry in the ARS dialed digits form is one with the 4 digits of the remote cluster element ID, and does not include any part of the remote extensions.  For example, I look in Controller A and see the remote cluster element ID as 8883.  In the ARS dialed digits form I see digits dialed 8883, number of digits to follow 4 and it points to the IP Trunk.  I don't get how a remote extension with digits 5678 is reachable by my phone sitting in Controller A.

I was hoping it was some simple Mitel concept I was failing to grasp, but this is pretty baffling to me.

[acejavelin]

I don't know how it could happen automagically without clustering and sharing, but nodes know where remote phones are because of the Remote Directory Number form...