Sending and Receiving Limitations on Calls and SMS Messages
Depending on your use case, the calling and sending rates will vary. Calls per second is an adjustable rate while messages per second is not. If you will be sending more messages or making more calls, 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.
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.
Inbound Calls and SMS
Twilio places no limitation on the rate at which a number can receive inbound calls or SMS messages. 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.
There is no rate limit on how many messages your Twilio phone number can send at a time. To protect your account from being filtered by carriers, messages cannot be sent more than 15 times in a 30 second window between your Twilio phone number and another number.
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 a rate of one message segment per second.
For example, if your SMS message is under 160 characters and does not include any non-GSM characters, it has 1 message segment, and will be released at the rate of one message per second. If your SMS message has 3 segments, a single message will be released every 3 seconds.
Depending on what your use case is, a short code may be a better option for you. Short code messages can be released at the rate of 30 messages per second. Check out our short code FAQ or talk to our sales team to determine what is best for you.
US and Canada Toll Free Numbers
On U.S. and Canadian toll-free phone numbers, the rate limit is 3 message segments per second. If an alphanumeric sender ID is used, you may send messages at the rate of 10 messages (or segments for longer messages) per second.