Handling one call at a time

This state diagram shows how to dial or answer one call at a time. It presumes there are no other calls being made by any other code.

The boxes are states. The 'E...' value in each box is the status of the phone's voice line. Voice line status describes these states and their meaning. You can also find the status of individual calls. However, when only one call is in progress then the line state and the call state are the same.

The arrows show events that trigger a change of state. In these events, a word in bold indicates a CTelephony method that you can call.

To dial or answer a call:

1. Check for other calls by getting the Voice line status.

   • If the line is Idle (CTelephony::EStatusIdle) then no calls are in progress

   • If the line is on hold (CTelephony::EStatusHold) then there is another call in progress, but it is on hold and you can still dial or answer a second call; see Handling Two Calls at once

   • Otherwise, another call is active: you must wait until it finishes before you can dial or receive a call. To detect when this occurs, see the example in How to get notification when information changes

2. Dialling a call

   While no calls are in progress, the line's status is CTelephony::EStatusIdle. To dial a call, use CTelephony::DialNewCall(); see Dial a call. If dialling was successful and the remotes party answers the call then the line's status will become CTelephony::EStatusConnected.

   Answering a call

   While no calls are in progress, the line's status is CTelephony::EStatusIdle. When a remote party calls your phone, the voice line's status will change to CTelephony::EStatusRinging. Detect an incoming call describes how to detect this change.

   When the status is CTelephony::EStatusRinging, use CTelephony::AnswerIncomingCall() to answer the call. The status will change to CTelephony::EStatusConnected and the phone user can talk to the remote party.

3. What next?

   You now have several options. They are the same for both answered calls and calls you dial yourself:

   • Terminate the call

   • Detect remote party terminating the call

   • Hold and resume the call

   • Send DTMF tones down the line

   • Find out about the call and the call; see Detailed line and call information and Remote party information

   When you successfully dial or answer a call, you will be given a CTelephony::TCallId the identifies the call. You must keep this safe - it is needed to perform each of the opeations above.

   At some point, a remote party might try to ring your phone. The voice line state will change to CTelephony::EStatusRinging. You can ignore this call; you can still terminate, hold, resume and send DTMF.