This training environment will introduce network helpdesk office. 3 ephones are configured with unique numbers but also with overlay button and third button is used for overlay line extension (x button). Each ephone can in future answer a call incoming from PSTN (call of clients calling to helpdesk).
name Worker 2
these number are individual
ephone-dn 4 to 6 introduce shared line feeling and overlay assignment enable equal response from all phones with ability answer call from other phones when any other is busy (in active call).
button 1:1 2o4,5,6 3x2
button 1 individual dn, button 2 is overlay (key system feeling), button 3 extend button 2 overlay line.
Configured ephones will looks like this