United States
Name

United States

ISO Code

US

Region

North America

Mobile Country Code

310, 311, 316

Dialing code

+1

Major carriers

AT&T, Verizon, T-Mobile, Sprint

Guidelines for United States
Two-way SMS supported

Yes

Number portability available

Yes

Twilio concatenated message support

Yes

Message length

1600 characters. Sprint does not support concatenation and messages will be delivered as multiple segments.

Twilio MMS support

Supported

Sending SMS to landline numbers

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.

Best practices

Twilio recommends sending application-to-person (A2P) traffic over short codes for optimal delivery results. Messages sent over over long codes are subject to carrier filtering, as A2P traffic is not permitted over US longcodes. Twilio does not definitively know how many messages can be sent from a long code before a user can expect to hit a filter. However, we highly recommend following the guidelines mentioned in Messaging Principals and Basic Practices published by CTIA in Jan. 2017, where CTIA suggests that Application-To-Peer (A2P) Messaging that's "consistent with typical human operation" should be expected to be deliverable across the messaging ecosystem. Some key attributes of typical human operation include:

Throughput: 15-60 messages per minute Unique Recipients: 200 unique recipients a day

The euro symbol (€) is not supported; avoid using this character in message submission toward the United States.

Twilio strongly encourages customers to review proposed use cases with qualified legal counsel to ensure 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.
Phone Numbers and Sender ID
Preregistered
Operator network capability

Not Available

Twilio supported

--

Sender ID format

--

Sender ID preserved

--

Two-way support

--

Provisioning time

--

Cost
--
Throughput (messages per second)
--
Use case restrictions
--
Best practices
--
Alphanumeric
Operator network capability

Not Available

Twilio supported

--

Sender ID format

--

Sender ID preserved

--

Two-way support

--

Provisioning time

--

Cost

--

Throughput (messages per second)

--

Use case restrictions

--

Best practices

--

Long Code
Operator network capability

Available

Twilio supported

Supported

Sender ID format

Local, Toll-Free

Sender ID preserved

Yes

Two-way support

Yes

Provisioning time

None

Cost

Refer to our pricing page

Throughput (messages per second)

1 message/second for local numbers, 3 messages/second for toll-free numbers

Use case restrictions

Application-to-person (A2P) messages sent via long codes may be subject to carrier filtering.

Learn more about carrier filtering

Best practices

As per the CTIA Messaging principles and Best Practices, we recommend sending to no more than 200 unique recipients per day from a Twilio long code at a rate of of no more than 15 - 60 messages per minute, to avoid possible carrier end filtering.

Short Code
Operator network capability

Available

Twilio supported

Supported

Sender ID format

5-6 digit numeric code

Sender ID preserved

Yes

Two-way support

Yes

Provisioning time

8-12 weeks

Cost
Throughput (messages per second)

100 messages/second or higher for an additional fee

Use case restrictions

A subset of short code use cases are prohibited by carriers.

You can find more detail on prohibited short code campaigns here.

Best practices

Refer to our FAQ for short code best practices about: + Mobile Marketing Opt-In + Help and Stop Standards + Opt-In Standards

The Twilio advantage
  • Communicate reliably

    Experience a 99.95% uptime SLA made possible with automated failover and zero maintenance windows.

  • Operate at scale

    Extend the same app you write once to new markets with configurable features for localization and compliance.

  • Many channels

    Use the same platform you know for voice, SMS, video, chat, two-factor authentication, and more.

  • No shenanigans

    Get to market faster with pay-as-you-go pricing, free support, and the freedom to scale up or down without contracts.