Avaya NN43112-101 Manuel D’Utilisation

single line. The local account for the active call appears on the context 
line. Each line key reflects the most active call state of its account.

The active call is affected by operations such as transfer or call parking. 
One exception is the New Call action, which uses the primary account by 
default; this can be overridden by pressing another line key to initiate the 
call.

Joining calls into a specific conference always uses the conference server 
of the primary account. Accounts which cannot access the server cannot 
join the server.

After you create a ad-hoc conference, you can join additional calls into the 
same conference. You cannot create more than one ad-hoc conference 
at a time. 

Three-way calls can join any two calls, regardless of the account. The 
service package of the account to which a call is associated determines 
which operations (for example, Call Park) are available on that call. After 
you have established a 3-way call, the join functionality becomes 
unavailable until the 3-way call is terminated.

 shows two examples of the 

Avaya 1120E IP Deskphone with one call and multiple calls.