on the EX90 check that you have added the multisite key. TC5 version would not harm neither.
Do not use a version
Some generic endpoint support info:
You can only have multiway or multisite, so if you have already configured the EX90 for multiway,
that will be the reason why you cant add an other local call, these features are exclusive to each other.
If you remove the multiway address it should work again with multisite.
Regards multisite conf, check on the
In short you need to enable autocreateing of conferences with no pin number prompt and have a MCU prefix
registration fitting your conference factory setting, not overlapping with your other conferences / tms
Besides that I recomend checking out the vcs, mcu and endpoint admin guides http://tandberg.com/docs is a good start
Bobby, please rate the answer with the stars below and set the thread to answered if it is!