The Telephony provider contains data related to phone operation, specifically SMS and MMS messages and access to the APN list, including the MMSC to use.

Note: These APIs are not available on all Android-powered devices. If your app depends on telephony features such as for managing SMS messages, include a <uses-feature> element in your manifest that declares the "android.hardware.telephony" hardware feature. Alternatively, you can check for telephony availability at runtime using either Android.Content.PM.PackageManager.HasSystemFeature(string) or Android.Telephony.TelephonyManager.PhoneType.

Creating an SMS app

Only the default SMS app (selected by the user in system settings) is able to write to the SMS Provider (the tables defined within the Telephony class) and only the default SMS app receives the NoType:android/provider/Telephony$Sms$Intents;Href=../../../reference/android/provider/Telephony.Sms.Intents.html#SMS_DELIVER_ACTION broadcast when the user receives an SMS or the NoType:android/provider/Telephony$Sms$Intents;Href=../../../reference/android/provider/Telephony.Sms.Intents.html#WAP_PUSH_DELIVER_ACTION broadcast when the user receives an MMS.

Any app that wants to behave as the user's default SMS app must handle the following intents:

• In a broadcast receiver, include an intent filter for NoType:android/provider/Telephony$Sms$Intents;Href=../../../reference/android/provider/Telephony.Sms.Intents.html#SMS_DELIVER_ACTION ("android.provider.Telephony.SMS_DELIVER"). The broadcast receiver must also require the NoType:android/Manifest$permission;Href=../../../reference/android/Manifest.permission.html#BROADCAST_SMS permission.
• In a broadcast receiver, include an intent filter for NoType:android/provider/Telephony$Sms$Intents;Href=../../../reference/android/provider/Telephony.Sms.Intents.html#WAP_PUSH_DELIVER_ACTION} ("android.provider.Telephony.WAP_PUSH_DELIVER") with the MIME type "application/vnd.wap.mms-message". The broadcast receiver must also require the NoType:android/Manifest$permission;Href=../../../reference/android/Manifest.permission.html#BROADCAST_WAP_PUSH permission.
• In your activity that delivers new messages, include an intent filter for Android.Content.Intent.ActionSendto ("android.intent.action.SENDTO" ) with schemas, sms:, smsto:, mms:, and mmsto:.
• In a service, include an intent filter for Android.Telephony.TelephonyManager.ActionRespondViaMessage ("android.intent.action.RESPOND_VIA_MESSAGE") with schemas, sms:, smsto:, mms:, and mmsto:. This service must also require the NoType:android/Manifest$permission;Href=../../../reference/android/Manifest.permission.html#SEND_RESPOND_VIA_MESSAGE permission.

This allows your app to directly receive incoming SMS messages.

This allows your app to directly receive incoming MMS messages.

This allows your app to receive intents from other apps that want to deliver a message.

This allows users to respond to incoming phone calls with an immediate text message using your app.

Other apps that are not selected as the default SMS app can only read the SMS Provider, but may also be notified when a new SMS arrives by listening for the NoType:android/provider/Telephony$Sms$Intents;Href=../../../reference/android/provider/Telephony.Sms.Intents.html#SMS_RECEIVED_ACTION broadcast, which is a non-abortable broadcast that may be delivered to multiple apps. This broadcast is intended for apps that&mdash;while not selected as the default SMS app&mdash;need to read special incoming messages such as to perform phone number verification.

For more information about building SMS apps, read the blog post, .

[Android Documentation]