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DID numbers · US +1

United States DID Numbers for inbound and CLI

Local numbers in United States that ring your SIP endpoint and double as verified outbound caller IDs. Order, document and route them from the portal.

North America+1
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key_facts · us
country_code
+1 · US
national_len
10 digits (NPA-NXX-XXXX)
mobile
No dedicated range: mobile and fixed numbers share NPA-NXX codes
fixed
Any geographic NPA, e.g. 212, 310, 312, 415, 713 · Toll-free: 800, 833, 844, 855, 866, 877, 888
regulator
Federal Communications Commission (FCC)
timezone
Six main time zones, from Eastern (UTC−5) to Hawaii (UTC−10).
reviewed
2026-10-28

Overview

DID numbers to United States

A DID (direct inward dialing) number gives you a real United States number on your SIP trunk. It receives calls from local customers and, because you hold it, it is also the strongest caller ID you can present on outbound traffic to United States.

US DIDs are available in most rate centres, plus toll-free numbers. Numbers you hold with us can be verified for A attestation, which makes them the strongest CLIs for your own outbound traffic.

The US is the largest destination for call-center and BPO traffic we carry. Answer rates depend heavily on how carriers and handset apps label the call, and that labelling depends on STIR/SHAKEN attestation and the reputation of the number you present.

Number formats
TypeE.164
Fixed+1 212 555 0142(212) 555-0142
Mobile+1 646 555 0187(646) 555-0187
Toll-free+1 800 555 01991-800-555-0199

+1 NPA NXX XXXX — 10-digit national numbers under the North American Numbering Plan.

Regulation · Federal Communications Commission

Caller ID rules in United States

A practical summary for operations teams, not legal advice. Confirm current requirements with counsel before you launch.

Last reviewed

Caller-ID presentation

The CLI must be a valid North American number you are entitled to use. FCC rules require telemarketers to transmit a number that can be called during business hours to opt out, and carriers block calls presenting invalid, unallocated or do-not-originate numbers outright.

Call authentication

STIR/SHAKEN has been mandatory on IP networks since June 2021 and now extends to intermediate providers. Every call carries an A, B or C attestation; A requires the signing provider to know the customer and confirm their right to the number. Foreign-originated calls enter through gateway providers that must be listed in the FCC Robocall Mitigation Database.

STIR/SHAKEN

Calls are signed and verified under STIR/SHAKEN. Full (A) attestation requires the originating provider to know the customer and confirm their right to use the number, which is why we verify CLI ownership at onboarding.

TCPA and the National DNC Registry

Telemarketing calls must respect the National Do Not Call Registry and internal opt-out lists. Prerecorded or artificial-voice calls to mobiles generally require prior express consent, and marketing calls require prior express written consent.

Truth in Caller ID Act

Transmitting misleading or inaccurate caller ID with intent to defraud or cause harm is prohibited. Telemarketers must transmit a number that can be called back during business hours.

Calling hours

The TCPA limits telephone solicitations to 8am–9pm in the called party’s local time. Several states set narrower windows.

Dialing & setup

Dialing United States correctly

  • Send 11 digits in E.164: +1 followed by NPA-NXX-XXXX. Strip any extra leading 1 your CRM adds.
  • Rotate CLIs only among numbers you hold and answer. Matching the called party’s area code (“neighbour spoofing”) is labelled aggressively by analytics engines.
  • Set CNAM (caller name) on your DIDs where supported; a business name improves answer rates on landlines.
  • Several states, including Florida and Oklahoma, have mini-TCPA laws with narrower calling hours and per-day call caps. Configure them per state in your dialer.

Caller ID best practice

Present numbers you own or are authorised to use, keep your CLI pool small and stable, register numbers with the major analytics and labelling platforms, and match CLI area codes to legitimate business presence rather than to the called party.

Troubleshooting

Common SIP errors on United States calls

  • 608

    Rejected

    An analytics engine blocked the call based on the CLI’s reputation (RFC 8688). Rest the number and review call patterns.

  • 603

    Decline

    The terminating carrier or the subscriber’s blocking app rejected the call. Often seen with low attestation.

  • 403

    Forbidden

    The CLI is invalid, unallocated or on a do-not-originate list, or the number is not authorised on your account.

Quality guidance

What healthy United States traffic looks like

US answer rates depend more on number reputation than on the route itself. A CLI labelled “Spam Likely” can halve ASR overnight, so watch ASR per number, not just per route.

35–55%

ASR

2.5–4.5min

ACD

2–5s

PDD

Typical ranges on healthy routes, as guidance only. Results depend on your lists, CLI reputation and campaign type. Live per-destination stats are in your portal.

Setup

Connect your DID number for United States

Replace the placeholders in angle brackets with the values from your portal. Full trunk templates for each platform are in the portal after sign-up.

Asterisk inbound route+1
; extensions.conf — inbound United States DID from CLIRoutes
[from-clirroutes]
exten => +12125550142,1,NoOp(Inbound United States DID)
 same => n,Set(CALLERID(name)=US support line)
 same => n,Goto(ivr-main,s,1)

; Present the same DID on outbound United States calls once it is verified.

FAQ

United States DID numbers: FAQ

Can’t find what you need? Our routing team answers within the hour, around the clock.

What attestation level will my US calls get?

It depends on your relationship to the number. Numbers you hold with us, or that you have documented authority to use, support A attestation. Unverified numbers can only receive B or C attestation, which increases the chance of a spam label.

Do you help with spam labels on US numbers?

We help you keep CLIs clean: we monitor answer-rate drops per number, advise on registering your numbers with the main analytics providers, and can supply fresh DIDs. We cannot remove labels applied by third parties, but verified, consistent use is the most reliable fix.

Do STIR/SHAKEN rules apply if my calls start outside the US?

Yes. Calls entering the US from abroad are signed by the gateway provider. Without verified rights to the number, they usually receive C attestation. Using US DIDs you hold and verifying them with us gives the best outcome.

What does a 608 Rejected response mean?

It means an analytics engine on the terminating side rejected the call because of the caller ID’s reputation. Pause that number, check short-call and complaint rates, and register it with the main analytics platforms.

Which state rules should my dialer enforce?

At minimum, state calling-hour windows and call-frequency caps where they exist (for example Florida’s three calls per 24 hours on the same subject). State laws change often, so review them with counsel each quarter.

What documents do I need for United States DIDs?

It depends on the number type. Many geographic numbers in United States require proof of a local address or business registration; toll-free and non-geographic numbers usually need less. The portal lists requirements per number type before you order.

Other products in United States

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Related guides

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United States DID Numbers

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