By they way, the limitation of 720p30 without the Premium Resolution option applies *only to transmitted and received video*.
Local video from a PC or SelfView will display at the native resolution up to 1080p60 or 1920x1200. We recommend that a 1080p or 1920x1200 monitor be used to avoid video scaling at the output of the SX20.
Yes, any standards-based SIP software client can connect to SX20 or any otther Cisco TelePresence endpoints. Cisco offers Cisco Jabber Video for TelePresence as a soft client for video.