933 read-back lab
Route a SIP phone or SBC to the E911HQ read-back service
Use this as a safe, inbound-only 933-style test target. Send a SIP call from a lab phone, PBX, cloud calling platform, or session border controller and the read-back service will speak back what arrived: caller ID, destination, location data when present, and the likely 911 answering center based on the best available location signal.
Primary test path
Send 933 to the SIP endpoint
Build a lab route pattern for 933 in your phone system or SBC and send the call to the SIP destination below. The point is to replicate the shape of an enterprise 911 call without placing a real emergency call. If your platform can attach PIDF-LO or SIP geolocation information, forward it so the read-back can confirm whether it survived the route.
| User part | 933 |
|---|---|
| Host | sip.e911hq.com |
| Port | 5060 for UDP/TCP. Use 5061 for TLS when your platform and the hosted voice edge are configured for it. |
| Codecs | G.711 u-law preferred for US testing. G.711 A-law is acceptable where your platform requires it. Avoid compressed codecs for first-pass validation. |
| DTMF | RFC 2833 / RTP events preferred. |
| Registration | No endpoint registration is required for the basic read back path. Send a SIP INVITE from your trusted SBC or SIP platform. |
- Preserve the calling number so the read-back can speak the caller ID that the receiving side observed.
- Forward SIP geolocation headers and PIDF-LO location objects if your platform supports them.
- Use a dedicated lab route, not your production 911 route, unless your carrier and emergency-routing provider have explicitly approved the test design.
- Capture the audio result and call detail record as evidence for migration, audit, or fire marshal readiness work.
PSTN inbound test
Call the public access number
You can also call from the regular phone network. The 901 number is only the access number for the read-back service. A PSTN call normally will not include PIDF-LO location data, so the read-back will say that no SIP location object was detected. It then looks at the caller ID of the person who dialed in and uses that caller ID geography as a rough PSAP hint.