ConceptShared line appearance (SLA) mimics the traditional KSU (key system unit) interface where all PSTN lines are shown on each phone, allowing users to hold and unhold calls from any phone.Intercom functionality does not work with Shared Line Appearance.The ability to put calls on hold and pick up calls from hold from any line will only work if your domain has MOH enabled. You can enable it by going to the Music on Hold tab then going to Settings.RulesNot all phones support shared line appearanceOne user (extension) can have many user devices (phones)SLA is supported for max 12 lines on each deviceThe same user device can only be assigned to one phoneExampleIn this example, we'll create SLA with lines 1000, 1001, 1002 to devices 000000000010, 000000000011, and 000000000012 (the number of lines and devices need not be equal).Create the line usersStart by creating the users 1000, 1001, and 1002 in the portal or admin UI. You may wish to enable voicemail on the first line but that's not mandatory, the following lines generally shouldn't have voicemail.Create User DevicesThen create user devices Users>Select the User>Phones) one per phone.  Generally, these would be 1000, 1000a, etc. Don't select a phone model - we're just creating the user device, not associating it yet.Setup Line HuntGo to Users and select the user then Answering RulesSelect the default rule and set Forward On Active to the next line userIf using voicemail, set a Forward No Answer to the mailbox on the first lineRepeat for the following lines, on the last line set the Forward On Active to voicemail.Assign Lines with SLAIn NDP or Portal Inventory create/edit the first device and add lines 1000, 1001, 1002. On the second device add lines 1000a, 1001a, 1002a. Follow with additional devices using lines b, c, etc. In Portal set SLA checked or in NDP set the "Share Type" as shared.You may optionally assign an extension for handset to handset calls, personal VM, etc. Then reboot the phones and test.Shared Line Appearance is when one button on multiple phones can be set up to share the same line. The line should have an LED associated with the button to indicate the status of the corresponding line. Upon an inbound call to the "Shared Line", all the available phones associated with the "Shared Line" will be rung, and the LED for the associated button should be flashing. The call can be answered at any of the associated phones simply by pressing the button associated with that line. Once the call is answered, the LED for the associated button will stay on continuously. Calls can be parked by pressing the button for that line and then retrieved by pressing the "shared line" button on any of the other associated phones. When the call ends, the LED associated with the line goes off on all of the phones. Outbound calls can be made by pressing the button to select one of the available "Shared Lines" (indicated by their associated LED being off), then dial the number you wish to dial.