Home > Lync EV > A Unique and clever method for providing Lync and legacy phone co-existance with minimal user pain

A Unique and clever method for providing Lync and legacy phone co-existance with minimal user pain

I recently have been at a client who has decided to move from Centrex based phones to Lync EV. This customer decided that doing a something like a weekend cut-over to Lync from their legacy phone system would be too drastic for end users, (about 15,000 people). This organization like many has legacy functions such as hunt groups, (e.g. 3 or 4 phones ring at the same time in a dept and anyone can answer). The team responsible for the move to Lync and eventual support of Lync decided that they needed a solution that allowed both “phone” systems to run in parallel so that users can use both Lync and their legacy phones while legacy functionality such as response/hunt groups can be migrated to Lync.

This customer came up with a somewhat unique and clever way allow Lync to run alongside the legacy system, and provide EV without changing the end user’s phone number. This particular customer is using Centrex, but this would easily apply to Cisco, Avaya, or other PBX infrastructures. This solution also has the added benefit of providing a path for the customer to stop using TDM voice and move to a SIP provider:

Lync and Centrex co-existence – how it is done:

• Customer purchased block of DIDs on a Windstream SIP trunk, (e.g. 202 475 xxxx)
• User is enabled for Lync and Lync EV
• User is enabled for Exchange UM for voice mail
• Current Centrix DID, (e.g. +1 303 444 1234) is saved as LineURI field (E.164 format)
• User is assigned a DID from the Windstream SIP trunk, (e.g. +1 202 475 1234)
• User’s SIP trunk DID is set as a Lync Unassigned number using set-csunassignednumber cmdlet
• A Lync Announcement is created that forwards calls to the unassigned SIP URI of the +1 202 475 1234 number to the LineURI of the user, (e.g. +1 303 444 1234). This is done by using set-csannouncement cmdlet BUT not assigning a greeting AND setting the -TargetURI parameter to the SIP address of the end users’ LineURI, (e.g. tel:+13034441234). This means that calls forwarded from the end users’ Centrex phone to their SIP trunk DID, (e.g. 1202 475 1234), to route to the unassigned number, ( +1202 475 1234) which plays NO greeting and itself is forwarded to the end users’ LineURI, (i.e. the -targetURI parameter of the set-csannouncement).
• At this point the following behavior occurs for a user:
o User maintains their current phone number
o User places calls from Lync via the SIP trunk and their CallerID is their Centrex number
o Calls placed to their Centrex number forward directly to their Lync client/phone
o If the user wishes to not receive calls on their Lync client they can turn off the autoforward. If they make calls from Lync their CallerID will still be their Centrex number
• At a later point in time the customer will begin porting the Centrex numbers over to the Windstream SIP trunk provider and start to get rid of Centrex phones.

Categories: Lync EV
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