I have tried to connect Spark to a Cisco Callmanager 7.01 using the SIP Phone plugin but it is not working. Here is what I did, and what I was able to troubleshoot. I created a SIP device on CUCM and tested it with X-Lite. The CUCM configuration is working and I am able to place and receive calls using X-Lite (If anyone is interested in how to configure CUCM, just send me a message). I configured the phone mapping in Openfire and started Spark. The phone plugin stays the following state forever: “Starting Phone…”. I did a SIP stack trace on the CUCM and a wireshark sniff on the client. Both indicate the same Problem: after successful registration the CUCM send a Notify to Spark, which is not acknowledged. Then CUCM repeats this and the connection does not work. I attached a picture of the working X-Lite wireshark trace as well as of the not working Spark trace. It would be great if anyone had an idea if this is a bug within the phone plugin or if there is anything I could do about this behavior.