SMS guidelines for United States
SMS works differently in every country. See how it works in United States.
310, 311, 316
AT&T, Verizon, T-Mobile, Sprint
1600 characters. Sprint does not support concatenation and messages will be delivered as multiple segments.
Twilio will not check whether the number is a landline and will attempt to send it to our carrier for delivery. Some carriers will convert the SMS into text-to-speech messages via voice calls.
Twilio recommends sending A2P traffic over short codes for optimal delivery results. When sending messages over long codes, we recommend sending no more than 250 messages per day per long code. Take advantage of Twilio's Messaging Services to send messages over a pool of phone numbers.
Twilio strongly encourages customers to review proposed use cases with qualified legal counsel to make sure that they comply with all applicable laws. The following are some general best practices: 1. Get opt-in consent from each end user before sending any communication to them, particular for marketing or other non-essential communications. 2. Only communicate during an end user's daytime hours unless it is urgent. 3. SMS campaigns should support HELP/STOP messages, and similar messages, in the end user's local language. 4. Do not contact end users on do-not-call or do-not-disturb registries.
Refer to our pricing page.
1 message/second for local numbers, 3 messages/second for toll free numbers
A2P messages sent via long codes may be subject to carrier filtering.
Learn more about carrier filtering.
We recommend sending no more than 250 messages per day from a Twilio long code to avoid possible carrier end filtering.
5-6 digit numeric code
Refer to our detailed short code pricing FAQ
30 messages/second or higher for an additional fee.
A subset of short code use cases are prohibited by carriers.
More detail on prohibited short code campaigns is available here.
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