SPA509G will not take firmware upgrade from 7.4.9a to 7.5.1a
Is your phone registered to a local PBX or to an external ITSP on the internet? If you are using an ITSP, they may or may not allow you to upgrade the firmware version, or may push your firmware version out to you.
You can always give us a call at 1-866-606-1866 and open a support ticket.
Configure Multicast Paging on the Cisco IP Phone 7800 Series or 8800 Series Multiplatform Phone
The Cisco IP Phone 7800 and 8800 Series Multiplatform Phones provide voice communication over an Internet Protocol (IP) network...
Add Call Park on a Cisco 7800 or 8800 Series Multiplatform Phone Key Expansion Module
Call park allows the user of the phone to put an incoming call on hold so that the call can be retrieved on another phone. A call is park...