You don't mention which model endpoints you are using, nor what software versions you are using on the endpoints or CMS, so it's hard to pinpoint exactly what you can do or not. Depending on hardware models and software versions, what you can do varies.
On the endpoint, there are two layout controls that you can issue on the endpoint itself to control how it displays stuff locally, and how it displays what it sends to the far end. Have a look at the SX20 Admin Guide for CE9.4 regarding the VIdeo DefaultLayoutFamily Local and Video DefaultLayoutFamily Remote settings for some commands which may help. Note - this is just for that single endpoint, it does not control the bridge itself. If you want to change the layout on the CMS, you would need to send DTMF tones in the call from the endpoint to the bridge to trigger the layout change (if you need to control it from the endpoint itself), or send API calls from somewhere else to the API of the CMS.
Wayne
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