Lync Push Notifications: 504 Timeout Error

I ran into an issue at a customer recently where push notifications for mobility were not working. Upon further investigation, the messages were receiving a 504 timeout with the Push Notification Clearing House (PNCH).


For reference, the push process interacts with the PNCH, and then on to the Apple or Microsoft Push Services. This happens through Lync Federation, through a Lync Edge Server.


When you are testing push notifications, Test-CSMCXPushNotification is the cmdlet to use. This will actually attempt to send a push message to the clearing house and report back any errors.

When using this cmdlet, use the following syntax: Test-CSMCXPushNotification – AcessEdgeFQDN <INTERNAL EDGE POOL>

In my case, the error below was displayed:

PS C:\Users\rwintle> Test-CsMcxPushNotification -AccessEdgeFqdn

Test-CsMcxPushNotification : A 504 (Server time-out) response was received from the network and the operation failed. See the exception details for more information.

At line:1 char:27

+ Test-CsMcxPushNotification <<<<  -AccessEdgeFqdn
+ CategoryInfo          : OperationStopped: (:) [Test-CsMcxPushNotificatio
n], FailureResponseException
+ FullyQualifiedErrorId : WorkflowNotCompleted,Microsoft.Rtc.Management.Sy

After some investigation, Microsoft has confirmed that the Federation SRV record is required for push notifications to work properly.

The PNCH will perform a look up on the SIP Domain for the Federation SRV record ( If this does not succeed, a 504 error will be thrown.

To fix this issue, you must configure that SRV record to point to your access edge server used for outbound Lync Push Federation Requests.


Posted on by Randy Wintle in Uncategorized 15 Comments

Why Lync Mobile Call-Via-Work Makes Sense



Earlier this week, Microsoft released the Lync 2010 Mobile clients for all major platforms. (See more about that here

With that release, a lot of people are talking about the lack of Voice over IP calling over 3G of Wifi in the product. Instead, Microsoft implemented a solution used for many years, referred to as “Call-Via Work”.

What is Call-Via-Work?

Call via work enables enterprises to deploy a consistently reliable enterprise voice solution to all mobile endpoints connecting to the Lync infrastructure. This functionality essentially bridges calls through the cell phone carrier network, and gives the appearance of a SIP call through your Lync identity.

This solution offers some great benefits:

  • A true “single number” solution, your identity is your work number. You can make or receive calls on this number from anydevice.
  • Battery friendly. This solution allows for users to actually utilize the tested and proven technology available on cell phones for years, reducing the impact on battery life when compared to a Voice over 3G, 4G or WiFi call.
  • Lync mobile users can call federated contacts.The call via work option allows users to make Lync calls to federated partners the same way it does to internal enterprise users, this is great because there is no gap in user capabilities from desktop to mobile.
  • I’ll say it again, Reliability! End users want a consistent experience, and do not want to be worried about the type of connection they are on when making a business call. Lets keep in mind, Lync is a business platform.

In some instances, VOIP makes sense, and lets face it, its kind of a popular technology right now. Everyone wants VOIP, not all end users know why they want it, but its just the new technology to use for most of them. However, it is important to understand that while it is a cool technology, with some potential for cost savings, a true enterprise grade solution cannot provide a reliable experience with VoIP on mobile devices, yet.

The potential savings that would be introduced through a VoIP solution deployed with Lync Mobile would definitely be eaten up by:

  • An overhaul of your Wireless Infrastructure. (If you want to deploy those fancy Cisco WAPs to support mobile VOIP, say good bye to any cost savings introduced by VOIP calling on your mobile)
  • Help Desk costs are a real problem in enterprise environments, these would definitely increase as users start having a poor experience when in an airport, or in a faux 4G area on an overloaded cell tower that provides limited bandwidth.
  • Costs for data vs cell minutes. Not many people know, but it isn’t always true that cell phone data is cheaper than cell phone minutes. Specifically when in roaming, and roaming international scenarios.In some instances, a roaming international 3G or 4G call could cost as much as 50 times more per minute than a roaming cell call…

So, to summarize:

Microsoft has done their research, they are not ignoring the fact that enabling mobile endpoints to communicate anywhere through their enterprise environment is important. What they are doing is deploying it properly! I would rather have a working, reliable solution, than have all the features in the world, that work half the time and provide me with a poor experience.


Posted on by Randy Wintle in Uncategorized 21 Comments