Lync Server and Shoretel Integration? – Absolutely

My intention of this post is to reach organizations whom currently leverage Shoretel and would like a high level understanding of integrating Lync Server 2010/2013 with their current Shoretel investment.  In this series of Q&A, it is assumed Lync will sit behind the Shoretel system.  In other words, the Shoretel PBX will be the gatekeeper for all Lync voice calls.
This is not the only approach as Lync can be designed to be placed beside Shoretel with both systems being “Front-Ended” by a Media Gateway.  Also, new in Lync Server 2013 is the ability to leverage inter-trunk routing so that Lync can now be placed in front of the Shoretel as well as any other PBX or IP-PBX system.  To learn more about inter-trunk routing, please visit Microsoft TechNet for details.  http://technet.microsoft.com/en-us/library/jj721940.aspx

High Level Questions Answered:

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Q: Can I integrate Shoretel and Lync Server for full Lync Server Enterprise Voice features without leveraging Shoretel Remote Call Control?
A: Absolutely and also the recommended approach from a Lync Server Voice perspective.
Q: Does the integration require Shoretel Hardware?
A: No. A simple 3^rd party Lync Certified gateway, such as an Audiocodes device is all that is required.
 Q: Shoretel uses UDP for SIP Trunks, does Lync Support UDP SIP Trunking?
A: No, this is why you must use a certified gateway between the 2 PBX systems.  A PBX that speaks SIP UDP cannot communicate directly (Direct SIP) to a PBX that speaks SIP TCP.

 Q: Can Lync Users dial Shoretel Users and vice versa?
A: Yes.  Depending on how your extensions and DID’s are configured in Shoretel, flexible Lync Server dial plans can be designed to retain Shoretel dialing habits.  With a correct design, calls between the two systems should stay on-net.
 Q: Can Lync Server provide Dial-in Conferencing capabilities while integrated to Shoretel?
A: Yes.  The ability to send a DID into Lync for conferencing uses the same method as to which Shoretel would send a number in for a Lync Enterprise Voice user.

Mid-Level Questions Answered:

Q: Can I integrate multiple Shoretel Voice Switches to Lync?
A: Yes.
 Q: Do I need more than 1 gateway to integrate multiple Shoretel Voice Switches across multiple locations?
A: Not at all.  An organization can very easily integrate a single gateway to a single Lync Server Pool and cover all Shoretel sites.  This topic is discussed and documented in detail as part of a Perficient Unified Communications project.
 Q: Do I need to consider the cost of Shoretel SIP Trunks?
A: Yes.  You should absolutely check with your Shoretel vendor to understand licensing agreements that may be in place with Shoretel and the cost associated with Shoretel SIP Trunks.   Also, it should be noted that Shoretel and Microsoft used the term “SIP Trunk” differently.  What may be referred to as Multiple SIP trunks on the Shoretel side, may only equate to a single SIP Trunk on the Lync Server side.
 Q: Does Microsoft license SIP Trunks for Lync Server?
A: No, licensing is based on CALs.  To learn more about Microsoft licensing, it is recommended that you speak with your Microsoft Licensing representative for a better understanding.

 Deeper Dive Questions Answered:

Q: Why should I integrate multiple Shoretel Voice Switches?
A: Shoretel voice switches allow you to allocate SIP Trunks in packs of 5 ports on the voice switches.  This allows for 5 concurrent calls.  If you do not have enough SIP Trunk ports available on a single switch, you may need to deploy an additional switch at that location to provide enough capacity.
 Q: Why should I build sip trunks to Shoretel Voice Switches in different sites?
A: A very quick reason is Voice Mail.  If remote sites have their own Shoretel Voice Mail Servers, a sip trunk to the Voice Switch at that location is required or the media flow to the Voice Mail server will fail.  Also, if SIP trunks are not defined for the remote site locations, all calls to and from that Shoretel location will be routed through your single Voice Switch that is integrated to the Lync certified gateway.  This could potentially impact performance and max out the SIP sessions on that single Voice Switch.
 Q: Can I share Shoretel Voice Switch SIP Trunk resources from multiple sites over a single Trunk Group?
A: No.  The site needs to provide its own SIP trunk back to the Lync Certified Gateway.
 Q: Can I send calls back and forth between the 2 systems using extension dialing?
A: Yes.   Lync offers easy to use and flexible dial plans.  However, as mentioned above, depending on how the Shoretel system is configured, extensive planning may be required to get the appropriate digit manipulations identified.
 Q. Can I configure dual forking to ring both my Shoretel and Lync endpoints?
A. Yes.  However, it is recommended to understand the technical limitations of this scenario as you may not get the desired results.  More importantly, however, administrators need to understand the complexity with dual forking between two voice systems and the impact on the end user.  Depending on the organizations desired goals, this may or may not be the best approach to a truly unified communications environment.
It is important to understand that Lync Server is a Unified Communications system in it of itself with voice capabilities as just part of its overall capabilities.  It is not designed to extend an existing telephoney infrastructure as it’s often percieved, but rather be its own solution by offering it’s own call control and conferencing capabilities.  If your organization wants to experience Lync to it’s fullest capabilities while retaining Shoretel or any other existing PBX, Lync should be designed, deployed and then users migrated to Lync as if it will eventually be your Unified Communications solution.  A user that is configured to use the 2 systems simultaneously may create negative perception and should be avoided.