E.164 Phone Format & DTMF Signal Helper
Format phone numbers to international ITU E.164 standards, generate RFC 4733 DTMF audio frequencies, and review call progress signaling standards (Dial Tone, Ringback, Busy).
DTMF Dialer Keypad
Click the keys or type on your keyboard to synthesize standard Dual-Tone Multi-Frequency (DTMF) telephony signals.
Call Progress Signals
Play loops representing standard call routing signals and telephone cadences.
Enter any phone number to parse and decode its country origin, area code location, format standard, and type.
Vertical Service Codes (Star Codes)
Common North American Numbering Plan (NANP) Vertical Service Codes used on analog lines, PBX setups, and VoIP adapters.
| Code | Service Name | Description & Cadence Behaviors |
|---|
Call Progress Tone Specifications
Standard frequency specifications for precise network tone plans (North American Precise Plan standard).
| Signal Type | Frequency Combo | Volume Level | Standard Cadence Description |
|---|---|---|---|
| Dial Tone | 350 Hz + 440 Hz | -13 dBm | Continuous tone until first digit dial input. |
| Busy Signal | 480 Hz + 620 Hz | -24 dBm | 0.5s On, 0.5s Off. Repeated cycles. |
| Ringback (Audible) | 440 Hz + 480 Hz | -19 dBm | 2.0s On, 4.0s Off. Repeats until answer. |
| Reorder (Fast Busy) | 480 Hz + 620 Hz | -24 dBm | 0.25s On, 0.25s Off. Signals network congestion. |
| Call Waiting Tone | 440 Hz | -13 dBm | 0.3s beep, silence for 9.7s. Overlaid on active call. |
| Off-Hook (ROH Howler) | 1400 + 2060 + 2450 + 2600 Hz | Dynamic (High) | 0.1s On, 0.1s Off. Pulsed sweep to alert of open receiver. |
ITU-T E.164 International Telecommunication Standard
E.164 defines the global public telecommunication numbering plan. Numbers can contain up to 15 digits including country code, national destination code, and subscriber number.
DTMF Dual-Tone Frequencies
DTMF signals mix a low-group row frequency (697–941 Hz) and a high-group column frequency (1209–1633 Hz) to represent keypad digits 0–9, *, #, and A–D.