I am currently developing a React Native app to send text messages. I successfully sent messages using smsManager.sendMultipartTextMessage(), but encountered an issue where some devices receive the messages as split parts. This seems to be a problem related to the carrier or the device itself, which I am unable to resolve. Therefore, I am looking to switch to sending MMS instead.

I tried using smsManager.sendMultimediaMessage() as described on this page: sendMultimediaMessage

However, I keep encountering failures, and I believe the issue might be related to creating the PDU file.

I referenced this site for the data format:
dataFormat

Despite numerous attempts, I haven’t been able to make it work, so I’m seeking help. How can I properly create the contentUri, which is the second parameter for smsManager.sendMultimediaMessage()?

The message should be sent in the background without opening the default messaging app.

my code is this

@ReactMethod
  public void sendDirectSms(String phoneNumber, String msg) {
    try {
      SmsManager smsManager = SmsManager.getDefault();
      // create MMS 
      ContentValues mmsValues = new ContentValues();
      mmsValues.put(Telephony.Mms.SUBJECT, "Subject");

      Uri mmsUri = this.context.getApplicationContext().getContentResolver().insert(Telephony.Mms.CONTENT_URI, mmsValues);
      if (mmsUri == null) {
        Log.e("SendDirectSms", "Failed to create MMS message.");
        return;
      }

      String messageId = mmsUri.getLastPathSegment();

      // add adress
      Uri addrUri = Uri.withAppendedPath(mmsUri, "addr");
      ContentValues addrValues = new ContentValues();
      addrValues.put(Telephony.Mms.Addr.MSG_ID, messageId);
      addrValues.put(Telephony.Mms.Addr.ADDRESS, phoneNumber);
      addrValues.put(Telephony.Mms.Addr.TYPE, 137);
      // addrValues.put(Telephony.Mms.Addr.TYPE, PduHeaders.TO);
      Uri insertedAddrUri = this.context.getApplicationContext().getContentResolver().insert(addrUri, addrValues);

      // // 3. add text part
      Uri partUri = Uri.withAppendedPath(mmsUri, "part");
      ContentValues partValues = new ContentValues();
      partValues.put(Telephony.Mms.Part.MSG_ID, messageId);
      partValues.put(Telephony.Mms.Part.CONTENT_TYPE, "text/plain");
      partValues.put(Telephony.Mms.Part.TEXT, msg);
      Uri insertedPartUri = context.getApplicationContext().getContentResolver().insert(partUri, partValues);

      smsManager.sendMultimediaMessage(this.context.getApplicationContext(), mmsUri, null, null, null);
    } catch (Exception ex) {
      System.out.println("couldn't send message.");
    }
  }

Whenever I attempt to send the MMS, no error messages appear, but when I check the default messaging app, the MMS is not sent.