语音来电等待与视频来电等待

[DESCRIPTION]
介绍语音来电等待与视频来电等待
[SOLUTION]
语音来电等待是指，语音通话期间，通知我有其他来电。
视频来电等待是指，视频通话期间，通知我有其他来电。
例A仅开启语音来电等待，
则A connected a voice call with B, C voice call/Video call A, A can be
notified ;
A connected a video call with B, C voice call A, A cannot be notified.
例 A仅开启视频来电等待，
则A connected a Video call with B, C voice call/Video call A, A can be
notified;
A connected a voice call with B, C video call A, A cannot be notified.

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