Much more intriguing are the white devices with some kind of black screen or speaker, two by two connected to a larger central device by two cables each. Only for president Trump there's a different device in silver grey, probably with a display folded up:
On the internet, there was speculation about the purpose of the mysterious devices. Some suggested that it could be small displays or microphone/speakers, but that seems less likely. Displays of that size would hardly add any useful functions and for such a small group there's no need for microphones and/or speakers in front of every participant: nowadays one single conference phone unit is sufficient for much larger conference tables (and the large Cisco EX90 screen has built-in microphones too).
Update:
In a thread on Reddit, someone said that the "hardened EX90 doesnt really have good microphone pickups, so we have to run a few external microphones thru the 1/8 mini microphone jack. Now they went a little crazy with the mic's but prolly went overboard because didnt want anyone complaining about not being heard. What you see is a Mini XLR cable and Sheilded POE cable that goes from each base station to the next."
However, another thread on Reddit is somewhat more in favor of jammer devices (see below).
There's also no reason why there should be such a series of devices when it comes to encryption: both video and audio from the standard Cisco equipment can easily be encrypted by a single network encryptor, like from General Dynamics's TACLANE series. In this way, the Defense Information Systems Agency (DISA) provides secure video teleconferencing over its Secret (SIPRNet) and Top Secret/SCI (JWICS) networks.
http://electrospaces.blogspot.com/2017/04/mysterious-devices-in-trumps-pop-up.html