Send a SMS via intent

Uri uri = Uri.parse("smsto:YOUR_SMS_NUMBER");   
Intent intent = new Intent(Intent.ACTION_SENDTO, uri);   
intent.putExtra("sms_body", "The SMS text");   
startActivity(intent);  

I have developed this functionality from one Blog. There are 2 ways you can send SMS.

1. Open native SMS composer
2. write your message and send from your Android application

This is the code of 1st method.

Main.xml

<?xml version="1.0" encoding="utf-8"?>  
    <RelativeLayout  
        android:id="@+id/relativeLayout1"  
        android:layout_width="fill_parent"  
        android:layout_height="fill_parent"  
        xmlns:android="http://schemas.android.com/apk/res/android">  

            <Button  
                android:id="@+id/btnSendSMS"  
               android:layout_height="wrap_content"  
               android:layout_width="wrap_content"  
               android:text="Send SMS"  
               android:layout_centerInParent="true"  
               android:onClick="sendSMS">  
           </Button>  
   </RelativeLayout>

Activity

public class SendSMSActivity extends Activity {  
     /** Called when the activity is first created. */  
     @Override  
     public void onCreate(Bundle savedInstanceState) {  
         super.onCreate(savedInstanceState);  
         setContentView(R.layout.main);  
      }  

     public void sendSMS(View v)  
     {  
         String number = "12346556";  // The number on which you want to send SMS  
         startActivity(new Intent(Intent.ACTION_VIEW, Uri.fromParts("sms", number, null)));  
     }  
    /* or 
     public void sendSMS(View v) 
      { 
     Uri uri = Uri.parse("smsto:12346556"); 
         Intent it = new Intent(Intent.ACTION_SENDTO, uri); 
         it.putExtra("sms_body", "Here you can set the SMS text to be sent"); 
         startActivity(it); 
      } */  
 }

NOTE:- In this method, you don’t require SEND_SMS permission inside the AndroidManifest.xml file.

For 2nd method refer to this BLOG. You will find a good explanation from here.

Hope this will help you...