smsManager.sendMultipartTextMessage(destAddress, null, divideContents, sentIntents, null);

next step --

android.telephony.SmsManager

public void sendMultipartTextMessage(

        String destinationAddress, String scAddress, ArrayList<String> parts,

        ArrayList<PendingIntent> sentIntents, ArrayList<PendingIntent> deliveryIntents) {

    if (TextUtils.isEmpty(destinationAddress)) {

        throw new IllegalArgumentException("Invalid destinationAddress");

    }

    if (parts == null || parts.size() < 1) {

        throw new IllegalArgumentException("Invalid message body");

    }

    if (parts.size() > 1) {

        try {

            ISms iccISms = ISms.Stub.asInterface(ServiceManager.getService("isms"));

            if (iccISms != null) {

                iccISms.sendMultipartText(destinationAddress, scAddress, parts,

                        sentIntents, deliveryIntents);

            }

        } catch (RemoteException ex) {

            // ignore it

        }

    } else {

        PendingIntent sentIntent = null;

        PendingIntent deliveryIntent = null;

        if (sentIntents != null && sentIntents.size() > 0) {

            sentIntent = sentIntents.get(0);

        }

        if (deliveryIntents != null && deliveryIntents.size() > 0) {

            deliveryIntent = deliveryIntents.get(0);

        }

        sendTextMessage(destinationAddress, scAddress, parts.get(0),

                sentIntent, deliveryIntent);

    }

}

next step --

com.android.internal.telephony.IccSmsInterfaceManager

public void sendMultipartText(String destAddr, String scAddr, List<String> parts,

        List<PendingIntent> sentIntents, List<PendingIntent> deliveryIntents) {

    mPhone.getContext().enforceCallingPermission(

            "android.permission.SEND_SMS",

            "Sending SMS message");

    if (Log.isLoggable("SMS", Log.VERBOSE)) {

        int i = 0;

        for (String part : parts) {

            log("sendMultipartText: destAddr=" + destAddr + ", srAddr=" + scAddr +

                    ", part[" + (i++) + "]=" + part);

        }

    }

    mDispatcher.sendMultipartText(destAddr, scAddr, (ArrayList<String>) parts,

            (ArrayList<PendingIntent>) sentIntents, (ArrayList<PendingIntent>) deliveryIntents);

}

next step --

com.android.internal.telephony.SmsDispatcher

protected void sendMultipartText(String destAddr, String scAddr,

        ArrayList<String> parts, ArrayList<PendingIntent> sentIntents,

        ArrayList<PendingIntent> deliveryIntents) {

    int refNumber = getNextConcatenatedRef() & 0x00FF;

    int msgCount = parts.size();

    int encoding = android.telephony.SmsMessage.ENCODING_UNKNOWN;

    mRemainingMessages = msgCount;

    TextEncodingDetails[] encodingForParts = new TextEncodingDetails[msgCount];

    for (int i = 0; i < msgCount; i++) {

        TextEncodingDetails details = calculateLength(parts.get(i), false);

        if (encoding != details.codeUnitSize

                && (encoding == android.telephony.SmsMessage.ENCODING_UNKNOWN

                        || encoding == android.telephony.SmsMessage.ENCODING_7BIT)) {

            encoding = details.codeUnitSize;

        }

        encodingForParts[i] = details;

    }

    for (int i = 0; i < msgCount; i++) {

        SmsHeader.ConcatRef concatRef = new SmsHeader.ConcatRef();

        concatRef.refNumber = refNumber;

        concatRef.seqNumber = i + 1;  // 1-based sequence

        concatRef.msgCount = msgCount;

        // TODO: We currently set this to true since our messaging app will never

        // send more than 255 parts (it converts the message to MMS well before that).

        // However, we should support 3rd party messaging apps that might need 16-bit

        // references

        // Note:  It's not sufficient to just flip this bit to true; it will have

        // ripple effects (several calculations assume 8-bit ref).

        concatRef.isEightBits = true;

        SmsHeader smsHeader = new SmsHeader();

        smsHeader.concatRef = concatRef;

        // Set the national language tables for 3GPP 7-bit encoding, if enabled.

        if (encoding == android.telephony.SmsMessage.ENCODING_7BIT) {

            smsHeader.languageTable = encodingForParts[i].languageTable;

            smsHeader.languageShiftTable = encodingForParts[i].languageShiftTable;

        }

        PendingIntent sentIntent = null;

        if (sentIntents != null && sentIntents.size() > i) {

            sentIntent = sentIntents.get(i);

        }

        PendingIntent deliveryIntent = null;

        if (deliveryIntents != null && deliveryIntents.size() > i) {

            deliveryIntent = deliveryIntents.get(i);

        }

        sendNewSubmitPdu(destAddr, scAddr, parts.get(i), smsHeader, encoding,

                sentIntent, deliveryIntent, (i == (msgCount - 1)));

    }

}

protected abstract void sendNewSubmitPdu(String destinationAddress, String scAddress,

        String message, SmsHeader smsHeader, int encoding,

        PendingIntent sentIntent, PendingIntent deliveryIntent, boolean lastPart);