For all of you that have been asking for the Key System functionality of shared Line buttons such as on the basic Norstar 3x8 or 8x24, the feature is currently in beta on the UCx and I've tried it out on my home system and it works wonderfully. See below:

Here is the Purpose & Benefits of the feature:

Purpose:
* To present external incoming calls on programmable keys on Nortel
extensions (I'll refer to them as SCA keys)
* Multiple Nortel extensions can be configured to have the same SCA
key(s)
* Once an incoming call is assigned an SCA ID, all extensions with the
corresponding SCA key provide indication of the call state via icons (IP
phones) or indicators (digital phones)
* While an SCA call is alerting, any extension on which the call is
offered can answer the call
* If an SCA call is put on hold, users of all phones with the
corresponding SCA key can press that key to retrieve the call

Benefits:
* SCA keys implement call appearances that can be shared by any number
of Nortel extensions
* SCA keys provide "public hold" functionality
* SCA keys provide visibility of how many incoming SCA calls are
active
* SCA keys can uniquely identify incoming trunks (configuration of SCA
keys is based on inbound routes - when a unique inbound route is used for
each trunk, one or more SCA keys can be configured to directly correspond to
each trunk)
* SCA keys can be configured on expansion modules (with SCA, the
number of active calls on a phone is not limited by the number of
programmable buttons on the phone itself)

Implementation notes:
* Configuration of SCA keys:
o Label - anything the user wants - for example "Call 1", "Call 2",
"Call 3" or "Line 1", "Line 2", "Line 3" etc.
o Number - must be a string in the format "SCA:@ route>". For example, for a call number 1 on inbound route "voipms", the
number field must be set to "SCA:1@voipms".
* The list of alerting extensions for SCA calls can include any phone
- with or without a corresponding SCA key, any technology (including SIP and
IAX).
* The state of SCA calls answered by phones without SCA keys or by
other technology phones (SIP/IAX) is correctly reflected on SCA keys. If
such a phone puts an SCA call on hold, the call can be retrieved from a
phone with the corresponding SCA key (by pressing that key) without any
limitations.
* Shared call appearances are defined based on an inbound routes. Due
to that, SCA keys for several routes can be configured on a single phone
(e.g., DID1 - call 1 to 3, DID2 - call 1 to 2, DID3 - call 1 to 4).
* On IP phones, white icons are used when the call is not active on
the phone, black icons are used when the call is active on the phone. For
digital phones, there are no white/black indicators so there is no
difference between active/inactive calls.
* With the exception of the extension's line appearance key, all
programmable keys on a phone can be configured as SCA keys. Due to that,
the limit for the number of calls on a single phone is equal to the number
of available programmable buttons. At this time, the SCA implementation
does not ensure that the programmable key has an indicator/icon - the
assumption is that such a key assignment would be useless and thus
administrators would not configure an SCA key on a button without an
indicator.
* Active calls on SCA keys are retained through configuration reloads
(even when the SCA key is moved). If an SCA key is removed from a phone
while there is an active call on that key, the call is dropped without
warning.
* SCA keys configured on an expansion module are dynamically
added/removed when the expansion module is connected/disconnected while the
phone is active (e.g., IP phone KEMs). If there is an active call on an SCA
key on an expansion module that has been removed, the call is dropped
without warning.

****New Forum - E-Metrotel UCx****
Joseph Sus-Nortel Installer/Programmer-"JoetheUCxguy" on Youtube
http://www.linkedin.com/pub/joe-sus/12/1a7/856