The service API is reasonably fast and works well however the expiry on credits means if you buy a lot of them and dont use them in a year, you end up loosing them or in some cases, even when you have thousands of credits left, in order to keep using those, you have to buy another lot in order to refresh the account as it seems if you havent paid them money for over 12 months, then credits become unuseable - they dont expire, the api stops accepting payuloads form your system using your account returning an error that is not at all clear about why its not working. I ended up designing my own system that uses a mobile app on my phone i write along with a web server and api so its now free for me to send unlimited sms with unlimited length per message. I ended up not using my lasy 6,000 credits and as they expired and i didnt want to by more, and they wouldnt refund me, i wasted them.