SendBulkSMS provides tiered service plans for sending and receiving both individual and bulk SMS messages. Features supported by SendBulkSMS include SMS delivery in over 200 countries, number validation, customizable sender identities, address book integration, delayed sending, templates, and contact management.
Their API lets developers integrate their systems with SendBulkSMS's services, allowing programmatic sending, receiving, and scheduling of SMS messages. The API also exposes functionality for checking account balances and managing contacts. This web service is available via HTTP, SOAP, and SMPP.