United States voice guidelines
United States voice guidelines
Voice calling guidelines for United States (US), covering reachability, caller ID formats, DTMF support, and emergency services.
Locale overview
| Field | Value |
|---|---|
| Country | United States |
| ISO code | US |
| Region | North America |
| Dialing code | +1 |
Reachability
All domestic, international, and toll-free number types support both inbound and outbound calling with no restrictions.
| Number type | Inbound | Outbound |
|---|---|---|
| Domestic | Supported | Supported |
| International | Supported | Supported |
| Toll-free | Supported | Supported |
Caller ID
Caller ID format varies by call type. International inbound caller ID is delivered on a best-effort basis and is not guaranteed.
| Call type | Direction | Format |
|---|---|---|
| Domestic | Inbound | +E.164 |
| Domestic | Outbound | +E.164 |
| International | Inbound | E.164 (non-guaranteed) |
| International | Outbound | +E.164 |
| Toll-free | Inbound | +E.164 |
| Toll-free | Outbound | +E.164 |
DTMF support
DTMF signaling uses RFC 2833 format and is supported for both inbound and outbound calls.
Emergency services
Calls to emergency numbers (911 and 933) are supported.
Best practices
- SHAKEN/STIR trusted calling registration is required to ensure call deliverability and provide caller verification indicators to called parties.
Compliance note
These guidelines summarize carrier requirements at the time of publication and do not constitute legal counsel. Verify that your implementation complies with all applicable telecommunications regulations in United States.