Please be sure your in-room systems have unique names. We have seen in-room systems (e.g. those joining via SIP or H.323 endpoints) drop when another attendee joins and their in-room system has the same name.
The only limit to the number of SIP or H.323 systems that can join a meeting is the total attendee count. The current max meeting size is 250 connections.
View the Amazon Chime User, Administration Guide and API Reference on the AWS Documentation site.
Find more information about the Amazon Chime solution, pricing, customer references, getting started, and other resources.