https://myatompark.com/ SMS client
Use as simple as:
AtomParkSmsSender sender = new AtomParkSmsSender(
"your_public_key",
"your_private_key"
);
//sender.getCampaignInfo( compain_id );
sender.sendMessage( "senderName", "some text", 380972223322L );
Instructions how to add dependency to your project: https://jitpack.io/#alexeytokar/atompark-sms