3.2.8. Alternating between Calls 
Not matter how many phone connections you are running at the same time, you can only conduct only one active call at a time. All other phone connections are automatically placed on-hold.
The signaling bars of the various phone connections are represented as tabs in the
tab bar. The tabs of held calls are grayed out. Using the controls in the tabs you
can decide which of the phone connections to deploy for conducting a call. This process
is called alternating between calls.
While connected simultaneously to two or more phone connections.
-
Click on
in the associated tab to place a currently
active call on-hold.The call is placed on-hold. -
Click on
in the associated tab of the tab bar to reconnect to a held call.The other call(s) are automatically placed on-hold.
Example
INFO:
It is not supported to Alternate/Reconnect between incoming calls established on a
preferred device being an External OND e.g. a mobile phone.
Alternating between these calls can only be administered via the external OND.
‣ Parent topic: Section 3.2. General Call Control