ANSI ISUP Originating Line Info Support


The ISUP OLI (also know as II digits) parameter includes information that is used for carriers to determine the origin of a call. This information gets lost over SIP networks if not inter-worked properly. This feature allows carrying ANSI ISUP OLI Parameter from traditional TDM network into SIP and vice versa.

This information is passed in the From: header of the INVITE message.


From: “Anonymous”<sip:+18182625511@;isup-oli=00>;tag=95ffcd055e0f78f7d5d397020e89288d63d4


Common ISUP-OLI codes

00 = Ordinary POTS call - not payphone

01 = Party line

02 = ANI Failure

27 = Payphone with network provided coin control

70 = Payphone without network provided coin control  



You enable this feature using the SIP From Header Tags pane. When this option is enabled, the IMG will include the INFO digits received in the Originating Line Info parameter (OLI) in the IAM message from the SS7 ANSI side into the ISUP_OLI tag in the From Header on the SIP side, and vice versa.


Call Flows:

SS7 to SIP

The following call flow shows where the IMG receives a call setup request from the PSTN/SS7 with the OLIP. With the ISUP-OLI feature this ISUP-OLI parameter will appear in the From header of the INVITE request




SIP to SS7

The following call flow shows where the IMG receives an INVITE with the From Header containing the ‘ISUP-OLI’ tag. With the ISUP-OLI feature, the IMG will send a call setup request to the PSTN/SS7 with the OLI parameter.