Changes

=== <h3> Proposal: Enhance telephony call states to hold a call ===</h3><p>The diagram below shows the current design of B2G telephony call states (white blocks) and the proposal for holding a call (yellow blocks).  We propose the waiting state because the extra waiting state helps the application understand that there has already been another connected call. If we only have the incoming state, then the application will need to retrieve extra information to know whether there is another call or not. </p><p><br/>  <br/p><p>  &#160;State transition in detail: </p>*<ul><li>Scenario #1: There is no other call on-line (current design)<br/>When a remote party dials, a new call is generated with its call index (no. 1), and the call state now is CALL_STATE_INCOMING.<br/>When user answers/hangs up the call, the call state is eventually pushed to CALL_STATE_CONNECTED/CALL_STATE_DISCONNECTED according to user's decision. *</li><li>Scenario #2: There is already a call on-line<br/>When the third party dials, a new call is generated with its call indexthe state of CALL_STATE_INCOMING. Since there is already a call on-line, the new call's index is no. 2. And the state of Call no. 2 is CALL_STATE_WAITING. When user answers the new call (call no. 2), its state is going to be transferred to CALL_STATE_CONNECTED. In the meanwhile, the state of the originally connected call (call no. 1) should be forced to CALL_STATE_HELD. |Answer()| an INCOMING call and |Answer()| a WAITING call are different. <br />*</li><li>Scenario #3: User wants to hold a call when there's no waiting call<br/>User can |HoldCall()| to change the call state from CALL_STATE_CONNECTED to CALL_STATE_HELD. User can |ResumeCall()| to make a call from CALL_STATE_HELD back to <br/>CALL_STATE_CONNECTED.</li></ul>[[Image:<p>&#160;<img src="/images/thumb/b/b9/Proposal_TelephonyCallStates_v2.png/777px-Proposal_TelephonyCallStates_v2.png" _fck_mw_filename="Proposal TelephonyCallStatesv2.png]] " _fck_mw_width="778" _fck_mw_height="865" alt="Proposal of telephony call states to support call holding" /><br/></p>