我找到了解决办法：
显然，它是CAPABILITY_CALL_PROVIDER，注册我的应用程序能够从电话堆栈中调用的那个。
让我复制一下我从Googles PhoneAccount类中找到的代码：

public class PhoneAccount implements Parcelable {
/**
 * Flag indicating that this {@code PhoneAccount} can act as a connection manager for
 * other connections. The {@link ConnectionService} associated with this {@code PhoneAccount}
 * will be allowed to manage phone calls including using its own proprietary phone-call
 * implementation (like VoIP calling) to make calls instead of the telephony stack.
 * <p>
 * When a user opts to place a call using the SIM-based telephony stack, the
 * {@link ConnectionService} associated with this {@code PhoneAccount} will be attempted first
 * if the user has explicitly selected it to be used as the default connection manager.
 * <p>
 * See {@link #getCapabilities}
 */
public static final int CAPABILITY_CONNECTION_MANAGER = 0x1;
/**
 * Flag indicating that this {@code PhoneAccount} can make phone calls in place of
 * traditional SIM-based telephony calls. This account will be treated as a distinct method
 * for placing calls alongside the traditional SIM-based telephony stack. This flag is
 * distinct from {@link #CAPABILITY_CONNECTION_MANAGER} in that it is not allowed to manage
 * calls from or use the built-in telephony stack to place its calls.
 * <p>
 * See {@link #getCapabilities}
 * <p>
 * {@hide}
 */
public static final int CAPABILITY_CALL_PROVIDER = 0x2;

我使用的不是CAPABILITY_CALL_PROVIDER，而是CAPABILITY_CONNECTION_MANAGER。行为相同，但我的应用不再显示为电话堆栈中的有效呼叫应用。