Microsoft Lync offers customers flexibility in deployment models with existing legacy IP-PBX systems through interoperability features like Direct SIP integration and Remote Call Control (RCC).
Direct SIP is the capability for Microsoft Lync to send and receive calls as a peer IP-PBX with existing telephony infrastructure, including SIP/PSTN Gateways and IP-PBXs. Dozens of PBXs, Gateways and IP Telephony Service providers interoperate with Microsoft Lync Server 2010 through Direct SIP. Those qualified for interoperability by a third party are documented in the Unified Communications Open Interoperability Program at http://technet.microsoft.com/UCOIP. Direct SIP allows end-users to have their entire phone capability served by Microsoft Lync as an alternative PBX infrastructure, or to work in concert with a PBX.
RCC is the capability for the Lync client to control a PBX phone through a Computer Telephony Integration (CTI) signaling channel with the PBX. RCC continues to be supported by Microsoft in Lync Server 2010. The core capabilities for end-users this feature provides is click-to-call using a user’s existing PBX phone and PBX-based binary presence update (“In a Call”). These capabilities are largely unchanged since the initial release of RCC with Live Communications Server 2005 SP1.
While RCC makes up a very small percentage (less than 1%) of deployed Lync voice seats, these capabilities continue to be supported for all customers in Lync Server 2010 although video calling for RCC-enabled users is not available in the Lync client. This includes both peer-to-peer video calling using the Lync client for both media types and split audio video calls where audio comes through the desk phone and video comes through the Lync client. The enhancements made in the Lync release, primarily around video escalation scenarios, required the video feature for RCC-configured users to be deprecated.
Based on feedback from customers planning to deploy Lync for RCC and video, Microsoft has investigated ways to address the lack of video capability for RCC-enabled users. Calling scenarios where audio is delivered through the desk phone and video comes through the Lync client, also known as “Split AV”, will continue to remain deprecated in Lync. The split AV scenario is not only is difficult from an engineering perspective, it provides an inconsistent and oftentimes suboptimal end-user experience with audio & video taking different network paths and losing sync.
Microsoft does plan to add peer-to-peer video calling for RCC-enabled users to the Lync client in the tentatively scheduled Q1CY12 timeframe. With this enhancement, RCC enabled users will be able to place and answer peer-to-peer Lync video calls, join conferences with audio and video enabled using Lync, and continue to use RCC for its core purpose of controlling the desk phone and binary presence update.
Microsoft does not have any additional information to provide about a future release of Lync. With the exception of this scheduled update, there are no planned changes or deprecation for the RCC feature set. Should any plans arise, Microsoft will announce them publically as soon as possible.
For end-users configured for RCC and deployed today without video calling capability (i.e. no webcams), there is no change to their experience with the current version of Lync. They will continue to control their PBX phone to place and receive calls using the Lync client as with previous releases. Similarly, presence update for a user’s “In a Call” status will still operate as expected. For a comparison of user features available in RCC vs Enterprise Voice, please refer to the Lync product documentation at http://technet.microsoft.com/Lync
Customers interested combining desktop video calling with IP telephony have several options for moving forward. In summary:
- Keep RCC users on Office Communicator 2007 R2, while deploying Lync to enterprise users for the voice features of Lync, either alongside or in replacement of their PBX phone.
- Use the Q1CY12 Lync update with peer to peer video calling enabled for RCC enabled users.
- Enable users for Enterprise Voice and use Direct SIP for trunk level interoperability with the IP-PBX.
Customers can continue to use the Microsoft Office Communicator 2007 R2 client for RCC users who require video capability. Most of the enhancements made to the Microsoft Lync client are for Enterprise Voice capabilities, and these features are largely absent for Lync end-users who continue to operate using RCC. As a result, RCC-configured users can remain on Communicator 2007 R2 and continue to use video calling capability. In addition, the Lync client can interoperate with the Communicator 2007 R2 client, so the population of users who do not require RCC with video can upgrade to Lync.
If peer-to-peer video calling for RCC users is desired in Lync, customers can deploy the update tentatively scheduled for availability in Q1 of CY12. From an end-user perspective, the change in user experience is that video calls and conferences will always have audio coming through the Lync client as opposed to having audio through the PBX phone. When a call is started on the PBX phone, the ability to add video will be disabled.
Alternatively, customers can deploy Lync but instead configure their users with the Enterprise Voice capabilities. This means end-users would have access to the large array of features found in Enterprise Voice, including simple PSTN dialing, sophisticated call management and integrated Exchange Unified Messaging. Using this configuration the CTI link between the PBX and Lync is not available so the RCC features of click-to-call using the PBX phone and PBX-based binary presence are not available. Instead, end-users would use custom presence to easily select “On my PBX Phone”. When using click-to-call, Microsoft Lync would place the outbound call instead of the PBX CTI connection.
The PBX phone can still continue to be used for conference calling with Lync, by having the Lync Server dial back to the PBX phone using Direct SIP. This does not require CTI resources on the PBX and can keep the phone instrument on the desk, operating as a normal PBX phone for inbound and outbound calling, with conference calls initiated by Lync’s “click-to-conference’ capability dialing back to the PBX phone. This gives the end-user both a PBX phone voice connection in addition to Lync’s collaboration features such as instant messaging and application sharing.