..... then you may want to take some of these points into consideration!

Hey guys,

I have recently completed a project deploying a highly available Cloud Link system and there were a few things that aren't exactly clear. Hopefully I can clear some of them up.

Call Transfer Issues


I was experience issues with transferring calls to other users, this included inbound calls from PSTN and Skype to Skype calls. When trying to transfer the call to another internal phone system user or to voicemail the incoming call would be put on hold and a message would appear stating that "Call Transfer has failed".


When troubleshooting the issue I would see 503 unavailable on the NOTIFY entry in the logs. The common theme was relating to not going through the SBC CCE integration wizard and that the configuration for Split DNS was not configured... once it was BAM forwarding was working.

At the end of the day it is great to manually do things to understand the process, but sometimes you may miss one little thing and it can cause a LOT of issues.

Consultative Transfer

After I though call transfer was working a specific transfer scenario was brought to my attention as not working... sigh 😫


PSTN > SfBO Auto Attendant > Reception Agent > Internal SfBO User > Reception Agent merges call > Both calls get put on hold.


Microsoft mention in "Configure Cloud Connector integration with your Office 365 tenant" section of the documentation to configure online hybrid mediation servers settings via the Skype for Business Online PowerShell. By configuring these mediation users SfBO conferencing servers will correctly INVITE the local CCE mediation servers which will result in peer-to-peer calls to be escalated to a PSTN conference successfully. Make sure to configure this.

Windows Server Update Services

When planning for CCE Guest VM Windows Updates there are two options which can be utilized - internet based updates or the user of a WSUS server.

If WSUS is intended to be used make sure to include the server IP address in the CloudConnector.ini (under WSUSServer) before starting the build. If you do not add this to the .ini file you will not be able to utilize WSUS as your system will become unsupported if you add this configuration later.

Cheers guys, let me know if you have any questions πŸ‘‹

Configure Cloud Connector integration with your Office 365 tenant
Learn how to configure Cloud Connector integration with your Office 365 tenant.