What are the limits on outbound calls and SMS messages per-second?
By default each Twilio account can make 1 outgoing call per-second. If your account needs more, please contact our sales team about options for higher limits.
SMS via Long Code
Each Twilio SMS-enabled long code (regular 10 digit number that excludes toll free numbers) can send 1 SMS message segment per-second, per-number. Unfortunately we are not able to adjust this rate limit. If your application requires a high volume of outgoing SMS, we recommend using an SMS short code.
SMS via US or Canadian Toll Free Long Code
US and Canadian toll free phone numbers have a rate limit of 3 message segments per-second, per-number.
For more details, please read “How quickly can I send SMS messages“?
SMS via Short Code
Inbound Calls and SMS
Twilio places no limitation on the rate at which a number can receive inbound calls or SMS messages. One thing to note here, though, is that Twilio will make an HTTP request to the request URL for each call and message received at your Twilio number. Therefore, please make sure your server is capable of handling the load if you are expecting a large amount of concurrent inbound traffic.