Lync 2013 Explained: Instant Message delivery in SPOP & MPOP scenarios

Lync Server 2013 supports several types of client software that you can deploy to your organization’s users, including computer-installed client software, web-based clients, and mobile devices.

Lync clients can further be differentiated into two categories

1. SIP clients: These clients use SIP Protocol primarily to sign-in to the Lync servers 

2. HTTPS clients : These clients use HTTPS to sign-in to the Lync servers 

    

Note: SIP client might use https protocol to connect for additional functionality however the SIP is primary registration protocol.

Lync Server 2013 also supports some of Lync 2010 client, for more information on Lync Server 2013 client please refer to https://technet.microsoft.com/en-us/library/gg398996.aspx

Let discuss more about SPOP & MPOP before we do that let’s run through some common understanding about presence. The user that publishes presence information is a presentity, whereas the users that consume this presence information are called watchers.

What is SPOP?

SPOP is single point of presence. At any one point in time Lync enabled user is just signed in one Lync client only to publish his presence. There is no other Lync client this user is using to communicate with the Lync server. There is only one endpoint registered for this user in Lync server database hence user can update his presence from this single endpoint only. This is no practical in today world

What is MPOP?

MPOP is multiple point of presence. At any one point in time a Lync enabled user is signed in using multiple Lync clients. There are multiple endpoint registered for this user in Lync server database hence user can update his presence from multiple endpoint. The server will aggregate this presence information and provide all ‘watchers’ a unified view of the presentities presence.

Note: One thing to keep in mind is that if you lock your device one of your Lync client but do not sign out Lync client or exit the Lync client or log off the user session on the device. Technically speaking Lync is still running on the device, and you are still MPOP’ed.

Instant message delivery

Lync server will only consider a message “delivered” if the conversation was actually accepted by receiver on the Lync client or if it is auto-accepted Lync desktop client.

Let look at instant message delivery in SPOP & MPOP message receiving scenarios between Lync clients

Scenario 1: SPOP: Sender is using Lync Desktop or laptop client and Receiver is using Lync Desktop or laptop client

Sender will send initial message to receiver or better known as an invite in Lync to the receiver. The receiver see will pops up a “toast” in the corner of their computer screen informing them about the request or invite. Since in this case user is signed in only one endpoint which is Lync desktop client, user has 15 seconds to respond to the request. If they do not respond the Lync desktop client will auto-accept the message and generate missed conversation on the receiver end   

Scenario 2: SPOP: Sender is using Lync Desktop or laptop client and Receiver is using Lync mobile client

Sender will send initial message to receiver or better known as an invite in Lync to the receiver. The receiver will get an alert informing them about the request or invite. Since in this case user is signed in only one endpoint which is Lync mobile client, user has 60 seconds to respond to the request. If they do not respond a missed conversation will be shown in Lync mobile client and sender will receive gets an error that the "Your message can't be delivered” Even though the receiver has received the message. 

Scenario 3: MPOP: Sender is using Lync Desktop or laptop client and Receiver is using multiple Lync clients

Sender will send initial message to receiver or better known as an invite in Lync to the receiver. The receiver depending on the Lync client they are using will see an alert or toast informing them about the request or invite on all the endpoints they are signed in from. Since in this case user is using multiple Lync clients, and if one these client is Lync desktop or laptop client user has 15 seconds to respond to the request. If they do not respond the Lync desktop client will auto-accept the message and generate missed conversation on all the receiver Lync clients  

A missed conversation will be shown in all the receivers Lync mobile client and sender will receive gets an error that the "Your message can't be delivered” Even though the receiver has received the message.

Summary

Lync server will only consider a message “delivered” if the conversation was actually accepted by receiver on the Lync client or if it is auto-accepted Lync desktop client. The message delivery notification might differ and is based on the Lync client or clients the receiver is logged into.