more documentation for SEND_RESPOND_VIA_MESSAGE

    /**

     * The Phone app sends this intent when a user opts to respond-via-message during an incoming

     * call. By default, the MMS app consumes this message and sends a text message to the caller. A

     * third party app can provide this functionality in lieu of MMS app by consuming this Intent

     * and sending the message using their own messaging system.  The intent contains a URI

     * describing the recipient, and an EXTRA containing the message itself.

     * call. By default, the device's default SMS app consumes this message and sends a text message

     * to the caller. A third party app can also provide this functionality by consuming this Intent

     * with a {@link android.app.Service} and sending the message using its own messaging system.

     * <p>The intent contains a URI (available from {@link android.content.Intent#getData})

     * describing the recipient, using either the {@code sms:}, {@code smsto:}, {@code mms:},

     * or {@code mmsto:} URI schema. Each of these URI schema carry the recipient information the

     * same way: the path part of the URI contains the recipient's phone number or a comma-separated

     * set of phone numbers if there are multiple recipients. For example, {@code

     * smsto:2065551234}.</p>

     *

     * <p>The intent may also contain extras for the message text (in {@link

     * android.content.Intent#EXTRA_TEXT}) and a message subject

     * (in {@link android.content.Intent#EXTRA_SUBJECT}).</p>

     *

     * <p class="note"><strong>Note:</strong>

     * The intent-filter which consumes this Intent needs to be in a service which requires the

     * The intent-filter that consumes this Intent needs to be in a {@link android.app.Service}

     * that requires the

     * permission {@link android.Manifest.permission#SEND_RESPOND_VIA_MESSAGE}.</p>

     *

     * <p>

     * {@link android.content.Intent#getData} is a URI describing the recipient of the message.

     * <p>

     * The {@link android.content.Intent#EXTRA_TEXT} extra contains the message

     * to send.

     * <p>For example, the service that receives this intent can be declared in the manifest file

     * with an intent filter like this:</p>

     * <pre>

     * <!-- Service that delivers SMS messages received from the phone "quick response" -->

     * <service android:name=".HeadlessSmsSendService"

     *          android:permission="android.permission.SEND_RESPOND_VIA_MESSAGE"

     *          android:exported="true" >

     *   <intent-filter>

     *     <action android:name="android.intent.action.RESPOND_VIA_MESSAGE" />

     *     <category android:name="android.intent.category.DEFAULT" />

     *     <data android:scheme="sms" />

     *     <data android:scheme="smsto" />

     *     <data android:scheme="mms" />

     *     <data android:scheme="mmsto" />

     *   </intent-filter>

     * &lt;/service></pre>

     * <p>

     * Output: nothing.

     */