Definition
Throughput, measured in TPS (transactions or messages per second), is the rate at which a provider accepts messages on an account, bind or route. Sending faster than the agreed TPS causes throttling or rejection.
TPS limits exist at several layers: the account, each SMPP bind or API key, the route to each operator, and the operator itself. The effective rate is the lowest of these.
On SMPP, exceeding the limit typically returns ESME_RTHROTTLED (0x00000058) in submit_sm_resp; on HTTP APIs it usually returns status 429. Clients should back off and retry rather than resend immediately.
For a campaign, divide the volume by the throughput to estimate send time. 100,000 messages at 50 TPS take about 33 minutes; multipart messages count once per segment on most platforms.
Time-critical traffic such as OTPs should not queue behind bulk campaigns. Separate binds, accounts or priorities for transactional and promotional traffic avoid that.