4-Line Appearance Service Use 4-Line Appearance Service to transform your Cisco or Polycom phone to a 4-line phone that can handle 4 calls at once (instead of the 2 active line keys). All 4 keys display the extension number of the phone and each line key can operate independently to handle incoming and outgoing calls. Great value for employees who juggle a lot of calls and need to toggle between them. Useful for receptionists or group administrative assistants who need to put multiple calls on hold to pick up later, transfer, etc. Works with: Cisco 504G and 525G2 Phones. Also see 8x8 Power Keys Service which bundles 4-Line Service and other services on Polycom sets.