Handling two calls at once

This state diagram shows how to dial or answer one or two calls at a time. It presume that no other code is making any calls; only you are making calls.

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; see Status of voice calls you own

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. Now go to point four below

   • 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?

   When you successfully dial or answer a call, you will be given a CTelephony::TCallId the identifies the call. You must keep this safe. To control your call (hang-up, hold, resume etc) you call CTelephony methods. Each method must be passed the ID of a call to operate on.

   Once a call is connected you have a number of options. You can perform these operations on your call. They are the same as those in Handling one call at a time:

   • 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

   In addition, you can dial or answer a second call:

   Answer a second call

   At some point, a remote party might try to ring your phone. It is answered in the same way as the first.

   The voice line state will change to CTelephony::EStatusRinging. You can receive notification when this occurs; see Detect an incoming call. Before answering the second call, you must put the original call on hold. This is shown in the diagram above.

   Dial a second call

   You can also dial a second call in the same way as the first. Once again, you must put your original call on hold before dialling the second call.

4. A CTelephony::TCallId will be given to you when you successfully connect a second call. You will also have a CTelephony::TCallId from the first call. Now you will be the owner of two calls: at any one time, one will always be active and one will always be on hold.

   Now you can:

   • Terminate either call. If you terminate the active call then you will be left with a call on hold. If you terminate the on-hold call then you will be left with an active call.

   • Detect remote party terminating either call. Once again, if the active call ends then you will be left with a call on hold and vice versa.

   • Swap held and active calls.

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