What is PIDF-LO?

Alex_Sberna — Wed, 07 Oct 2026 21:38:35 GMT

For IP-based calling, location is not always tied to a fixed line. PIDF-LO helps ensure the correct address is sent with the call itself when dialing for emergency services. PIDF-LO stands for Presence Information Data Format - Location Object. With Sinch Elastic SIP Trunking, PIDF-LO can be used to pass the caller's location so emergency services systems can receive and process that information in the event that the caller cannot communicate. PIDF-LO support is enabled on all trunks by default.

To test PIDF-LO on the Sinch network, dial 933. When you call 933:

we answer the call
we repeat back the address we received.

This allows you to confirm that your location information is being delivered correctly before relying on it for emergency calling. This is a simple way to confirm that your PIDF-LO location data is being delivered correctly before relying on it for 911 calling.

Example SIP Headers

A packet capture or SIP trace with PIDF-LO typically includes a Geolocation header and a PIDF-LO body. A simplified example looks like this:

INVITE sip:911@example.com SIP/2.0 Via: SIP/2.0/UDP 203.0.113.10:5060;branch=z9hG4bK-12345 From: <sip:+12025550100@example.com>;tag=abc123 To: <sip:911@example.com> Call-ID: 1234567890@example.com CSeq: 1 INVITE Contact: <sip:+12025550100@203.0.113.10:5060> Geolocation: <cid:location1@example.com> Geolocation-Routing: yes Content-Type: multipart/mixed;boundary=boundary42 Content-Length: ... --boundary42 Content-Type: application/sdp v=0 ... --boundary42 Content-Type: application/pidf+xml Content-ID: <location1@example.com> <?xml version="1.0" encoding="UTF-8"?> <presence xmlns="urn:ietf:params:xml:ns:pidf" xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10" xmlns:cl="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr" entity="pres:caller@example.com"> <tuple id="t1"> <status><basic>open</basic></status> <gp:geopriv> <gp:location-info> <cl:civicAddress> <cl:A1>NC</cl:A1> <cl:A3>Raleigh</cl:A3> <cl:RD>Main Street</cl:RD> <cl:HNO>123</cl:HNO> <cl:PC>27601</cl:PC> </cl:civicAddress> </gp:location-info> </gp:geopriv> </tuple> </presence> --boundary42--

article What is PIDF-LO? in Elastic SIP Trunking

What is PIDF-LO?

Example SIP Headers