How come I cannot find any information on these phones anywhere?

However, there is a line of Cisco 500 series phones: 521G, 521SG, 524G, 524SG (http://www.cisco.com/en/US/prod/collateral/voicesw/ps6788/vcallcon/ps7293/data_sheet_c78-466719_ps9730_Products_Data_Sheet.html). Along with them, SPA-525G is also mentioned (http://www.cisco.com/en/US/products/ps10067/index.html).

All Cisco 500 series phones support only SPCP (a modified version of SCCP) and work with only UC-500 system running Cisco Unified Communications Manager Express (CUCME). They do not work with Cisco Integrated Services Routers (ISRs) running CUCME or with Cisco Unified Communications Manager (CUCM). However, SPA-525G supports both SPCP and SIP, and as a SIP client, it works with any SIP based PBX, including CUCME running on any ISR. So, do SPA-501G, SPA-502G, SPA-504G, SPA-508G, and SPA-509G support both SPCP and SIP? Also, the USB port you have mentioned is used to connect any USB-based storage device from which the phone can stream media via a built-in MP3 player in the phone’s software.

The phones shown here will be officially announced by Cisco any day now.

Watch out if you get these phones! I’ve spent two months trying to straighten out the mess that they cause. It’s like the old addage says ‘you get what you pay for’. DSPs keep crashing in my UC. Cisco SE came in and didn’t know what was up…