I havent faced the issue. All i get is the service messages for data consumption every now and then. You sure it is sending messages? Or is it something regarding data? And my overnight battery consumption without wifi and data (2G only mode, data off) is about 7-8 %. I did face a random speaker rattle with android apps in the beginning though. Whenever i opened a chat app like whatsapp or telegram(Those are the only android apps i have) , the speaker made a faint rattle sound. It happened in some combination of sound setting which i havent been able to pinpoint yet. But i havent experienced that after the first two days.