MessageCloud's SMSC HTTP API enables you to send lots of SMS messages in a short period of time.
The HTTP interface to our SMSC has been benchmarked at over 100 transactions per second from an individual service account, using parallel HTTP requests and measured using Apache JMeter. The default service account configuration provides 10 concurrent HTTP connections. If your service requires more than this then please contact an account manager.
If you want to use the SMSC with SMPP, a protocol for sending medium to large batches of SMS through a single connection, then take a look at our SMPP API.