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 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.

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
--
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

A2P messages sent via long codes may be subject to carrier filtering.

Learn more about carrier filtering.

Best practices

We recommend sending no more than 250 messages per day from a Twilio long code to avoid possible carrier end filtering.

Short Code
Operator network capability

Available

Twilio supported

Supported

Sender ID format

5-6 digit numeric code

--
Two-way support

Yes

Provisioning time

8-12 weeks

Cost
Throughput (messages per second)

30 messages/second or higher for an additional fee.

Use case restrictions

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

More detail on prohibited short code campaigns is available 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
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  • 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.