How to start Viber call from an Android app [new version]?

Question 1

According to Viber's manifest, there is activity "com.viber.voip.phone.PhoneActivity" that is responsible for action "com.viber.voip.action.CALL". In new version of Viber (4.2.1.1) this activity is marked by android:exported="false". As result, it's not possible anymore to start this activity from external applications...

Edit

This code opens welcome screen for specified contact

String sphone = "12345678";
Uri uri = Uri.parse("tel:" + Uri.encode(sphone)); 
Intent intent = new Intent("android.intent.action.VIEW");
intent.setClassName("com.viber.voip", "com.viber.voip.WelcomeActivity");
intent.setData(uri); 
context.startActivity(intent);

but user should click button "free call" to start call.

Question 2

It is possible to call per Viber direct (without WelcomeActivity), but user should have this number in Contacts.

public void callToViberContact(String phoneNumber, Context context) {
    Uri uri = getUriFromPhoneNumber(phoneNumber, context);
    if (uri != null) {
        Intent intent = new Intent("android.intent.action.VIEW");
        intent.setClassName("com.viber.voip", "com.viber.voip.SystemDialogActivityPublic");
        intent.setData(uri);
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(intent);
    } else {
        Toast.makeText(context, "Number is not in Viber Contacts List", Toast.LENGTH_LONG).show();
    }
}

private Uri getUriFromPhoneNumber(String phoneNumber, Context context) {
    Uri uri = null;
    String contactId = getContactIdByPhoneNumber(phoneNumber, context);
    if (!TextUtils.isEmpty(contactId)) {
        Cursor cursor = context.getContentResolver().query(
                ContactsContract.Data.CONTENT_URI, new String[]{ContactsContract.Data._ID},
                ContactsContract.Data.DATA2 + "=? AND " + ContactsContract.Data.CONTACT_ID + " = ?",
                new String[]{"Viber", contactId}, null);
        if (cursor != null) {
            while (cursor.moveToNext()){
                String id = cursor.getString(cursor.getColumnIndexOrThrow(ContactsContract.Data._ID));
                if (!TextUtils.isEmpty(id)) {
                    uri = Uri.parse(ContactsContract.Data.CONTENT_URI + "/" + id);
                    break;
                }
            }
            cursor.close();
        }
    }
    return uri;
}

private String getContactIdByPhoneNumber(String phoneNumber, Context context) {
    ContentResolver contentResolver = context.getContentResolver();
    String contactId = null;
    Uri uri = Uri.withAppendedPath(ContactsContract.PhoneLookup.CONTENT_FILTER_URI, Uri.encode(phoneNumber));

    String[] projection = new String[]{ContactsContract.PhoneLookup._ID};

    Cursor cursor =
            contentResolver.query(
                    uri,
                    projection,
                    null,
                    null,
                    null);

    if (cursor != null) {
        while (cursor.moveToNext()) {
            contactId = cursor.getString(cursor.getColumnIndexOrThrow(ContactsContract.PhoneLookup._ID));
        }
        cursor.close();
    }
    return contactId;
}

READ_CONTACTS permission is required. Don't forget to add in Manifest:

<uses-permission android:name="android.permission.READ_CONTACTS" />

Question 3

String uriString = "content://com.android.contacts/data/" + _id;

Intent intent = new Intent();
intent.setAction(Intent.ACTION_VIEW);
intent.setData(Uri.parse(uriString));
intent.setPackage(PKG_VIBER);
startActivity(intent);

_id can be queried from contacts2.db(Column ContactsContract.Data._ID)