Twilio imposes some rate restrictions on certain calls and message products. This guide explains the limitations.
The default outbound call rate is 1 call per second (CPS), but there are other factors that may affect calls using Twilio's Programmable Voice, Client, and Elastic SIP Trunking products.
For full details, see How fast can I place or receive phone calls with Twilio.
SMS text messaging
The default outbound SMS message rate is 1 message segment per second (MPS) on SMS-capable long codes in the US and Canada, but this rate varies for different phone number types and originating countries.
For full details, see Understanding Twilio rate limits and message queues.
MMS multimedia messaging
The default outbound MMS message rate is 1 MMS message per second (MPS) on SMS-capable long codes in the US and Canada, but there is also an Account SID rate limit.
For full details, see Twilio multimedia messaging (MMS) account rate limits.
Outbound voice call and short code SMS throughput increases are available for a monthly fee. For pricing inquiries, please reach out to your Account Manager, or contact Sales.