Hello - we have a mix of SX 10's 20's and 80's in our network. They all register to CUCM 10.5. The codecs are on TC 7.3.4 and we do not have the multisite license for any of them as we use an external bridge for more than point to point.
When on a video call with an SX20 a second audio call can be brought into the conference. When we try to attempt the same thing with the SX10 all parties go to audio and the video goes away when the second audio call is dropped the point to point video re-establishes. IS this a limitation with the SX10?
I'm not in front of an SX10, but you can check how many active calls the SX10 is capable of using the web interface, go to: Configuration > System Status > SystemUnit. My assumption, and looking at the data sheet, is that it's only capable of supporting one active call at a time due to it being an entry level endpoint and it might not support the processing power to host multiple calls at the same time.