Sending and Receiving Limitations on Calls and SMS Messages

Inbound and outbound call rates

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.

For inbound calls, Twilio places no limitation on the rate at which a number can receive inbound calls. Twilio will make an HTTP request to the request URL for each call 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.

Sending and Receiving Limitations on SMS Messages

Depending on your use case, the sending rates will vary. If you will be sending more messages, you can purchase additional numbers. Also please note that while Twilio releases messages and calls to our carrier partner(s) at the rates below, your messages may be subject to mobile carrier filtering and can get blocked by the carrier(s) – read the article Can my Twilio SMS messages be blacklisted as spam? to learn more.

Inbound SMS

Twilio places no limitation on the rate at which a number can receive SMS messages. Twilio will make an HTTP request to the request URL for each 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.

Outgoing SMS on Long Codes

Based on the destination you’re reaching, your messages will be processed at different rates. If your application is making requests faster than the rate mentioned below, your messages will be placed in a queue and processed accordingly.

FromToMessages per Second
Twilio SMS-capable local or mobile numberUS and Canada1
Twilio US toll free numberUS and Canada3
Any Twilio SMS-capable number or Alphanumeric sender IDOther international countries10
Twilio short codeUS, Canada or UK

30

(contact sales for more)

 

Processing Long/Concatenated Messages

If you have a message with multiple segments (a message over 160 characters will be broken up into 160-character segments), Twilio will queue the messages and release them at the rate of one message segment per second.

For example, if your SMS message to a US mobile number is under 160 characters and does not include any non-GSM characters, it only has one message segment, and will be released at the rate of one message per second. If your SMS message has three segments, it’ll take three seconds to delivery that single message.

Loop protection

To protect your account, messages cannot be sent more than 15 times in a 30 second window between your Twilio phone number and another number. Doing so may trigger a 14107 warning that your message rate has been exceeded.