SS7 Headers

Owned by Kelli Higdon
Last updated: Mar 18, 2024
2 min read

 

What are SS7 Headers?

SS7 headers are used to set message information & send via SS7 protocol.
NSG maps SS7 information elements into SS7/SIP messages in order to pass specific SS7 parameters to the end user.

 

NSG usesSS7 headers to pass SS7 variables from SS7->SS7 & SS7->SIP (i.e. CIC, NADI, RDNIS..etc)

 

Passing information from SS7→SS7/SS7→SIP

By default if NSG receives a SS7 message with any of the SS7-Headers defined below and the SS7-Headers feature is enabled, NSG will automatically populate the associated SS7 messages with the specified values.  A SS7-Header will only be considered if it is properly formed, and matches the string found in the "SS7-Header" column below, and is case-insensitive.

FreeSWITCH - How to Use SS7 Headers

SS7->SIP (Receiving SS7 Header From NSG) 

SS7 header will be stored in the FreeSWITCH variable "freetdm_Z" with Z being the SS7 header.
The example below will print to the log/console the value of the SS7 header that contains the cic number the call is on.

Example

<action application="log" data="The CIC Number Is: [${freetdm_ss7_cic}]"/>

 

SIP->SS7 (Sending SS7 Header To NSG)

You can populate an SS7 header by using the "export" application in FreeSWITCH.
The example below shows how to set the RDNIS NADI value to 4.

Example

 <action application="export" data="freetdm_ss7_rdnis_nadi=4"/> 

NOTE

  1. While setting  SS7 header from dialplan we always needs to use freetdm as a prefix to SS7 Headers for example if we need to set redirection nadi then in dialplan we need to use variable as freetdm_Z as explained before as shown below:

<action application="export" data="freetdm_ss7_rdnis_nadi=4"/> 

  1. SS7-> SS7 means when parameters can be exported from SS7 to SS7.
        SS7->SIP means when parameters can be exported form SS7 to SIP .
        If "Y"  than that parameter can be set and exported/set. If "N" then it is not. 

 

Complete List of SS7 Headers

 General

SS7-Header

Description 

SS7->SS7

SS7->SIP 

ss7_clg_num

Calling Number

Y

N

ss7_orig_clg_num

Original Calling Number

Y

N

ss7_iam_fwd_ind_hex

Forward Call Indicator in HEX

Y

Y

ss7_iam_nature_connection_hex

Nature of Connection Indicator in HEX

Y

Y

ss7_iam_priority

IAM Message Priority

Y

Y

ss7_screen_ind

Screening Indicator

Y

Y

ss7_pres_ind

Presentation Indicator

Y

Y

ss7_access_transport_urlenc

Access Transport IE encoded

Y

Y

ss7_hopCounter_val

Hop Counter

Y

Y

ss7_usr2UsrInfo_val

User to User Information

Y

Y

ss7_num_port_fwd_info_status_ind

Number Portability Forward Information Status Indication

Y

N

ss7_num_port_fwd_info_status_ext

Number Portability Forward Information Extension Indicator

Y

N


Advanced 

SS7-Header

Description 

SS7->SS7 

SS7->SIP 

ss7_cic

CIC Number

Y

N

ss7_opc

Originating Point Code

Y

N

ss7_clg_nadi

ANI Nature of Address Indicator

Y

Y

ss7_cld_nadi

DNIS Nature of Address Indicator

Y

Y

 

Redirected Dialed Number

SS7-Header

Description 

SS7->SS7 

SS7->SIP 

ss7_rdnis_digits

Redirected Dialed Number

Y

Y

ss7_rdnis_nadi

RDNIS Nature of Address Indicator

Y

Y

ss7_rdnis_plan

RDNIS Numbering Plan

Y

Y

ss7_rdnis_screen_ind

RDNIS Screening Indicator

Y

Y

ss7_rdnis_pres_ind

RDNIS Presentation Indicator

Y

Y

 

Generic Number/Generic Number Repeated

SS7-Header

Description 

SS7->SS7 

SS7->SIP 

ss7_gn_digits / ss7_gn_repeated_digits

Generic Number

Y

Y

ss7_gn_numqual / ss7_gn_repeated_numqual

GN Qualifier

Y

Y

ss7_gn_nadi / ss7_gn_repeated_nadi

GN Nature of Address Indicator

Y

Y

ss7_gn_screen_ind / ss7_gn_repeated_screen_ind

GN Screening Indicator

Y

Y

ss7_gn_pres_ind / ss7_gn_repeated_pres_ind

GN Presentation Indicator

Y

Y

ss7_gn_npi / ss7_gn_repeated_npi

GN Numbering Plan

Y

Y

ss7_gn_num_inc_ind / 
ss7_gn_repeated_num_inc_ind

GN Number Incomplete Indicator

Y

Y

 

Location Number

SS7-Header

Description 

SS7->SS7 

SS7->SIP 

ss7_loc_digits

Location Number

Y

Y

ss7_loc_screen_ind

LOC Screening Indicator

Y

Y

ss7_loc_pres_ind

LOC Presentation Indicator

Y

Y

ss7_loc_nadi

LOC Nature of Address Indicator

Y

Y

 

Redirection Information Number

SS7-Header

Description 

SS7->SS7 

SS7->SIP 

ss7_rdinfo_indicator

RDINF Indicator

Y

Y

ss7_rdinfo_orig

RDINF Original Reason

Y

Y

ss7_rdinfo_count

RDINF Redirection Count

Y

Y

ss7_rdinfo_reason

RDINF Reason

Y

Y

 

Original Called Number

SS7-Header

Description 

SS7->SS7 

SS7->SIP 

ss7_ocn

OCN number

Y

Y

ss7_ocn_nadi

OCN Nature of Address Indicator

Y

Y

ss7_ocn_plan

OCN Plan

Y

Y

ss7_ocn_pres

OCN Presentation Indicator

Y

Y


IAM User Service Information Parameter

SS7-Header

Description 

SS7->SS7 

SS7->SIP 

ss7_iam_usi_trans_cap

Information transfer capability

Y

N

ss7_iam_usi_code_standard

Coding standard

Y

N

ss7_iam_usi_trans_mode

Transfer mode

Y

N

ss7_iam_usi_trans_rate_0

Information Transfer Rate

Y

N

ss7_iam_usi_layer1_ident

Layer 1 identity

Y

N

ss7_iam_usi_layer1_prot

User Information Layer 1 protocol

Y

N

ss7_iam_usi_layer2_ident

Layer 2 identity

Y

N

ss7_iam_usi_layer2_prot

User Information Layer 2 protocol

Y

N

ss7_iam_usi_layer3_ident

Layer 3 identity

Y

N

ss7_iam_usi_layer3_prot

User Information Layer 3 protocol

Y

N

ss7_iam_usi_chan_struct

Channel Structure

Y

N

ss7_iam_usi_config

USI Configuration

Y

N

ss7_iam_usi_establish

USI establishment

Y

N

ss7_iam_usi_symmetry

USI symmetry

Y

N

ss7_iam_usi_rate_multiplier

Rate Multiplier

Y

N

 

ITX Message Parameter

SS7-Header

Description 

SS7->SS7 

SS7->SIP 

ss7_itx_charge_unit

Charge Unit Number

Y

N

ss7_itx_msg_num

Message Number

Y

N


SS7 UK Parameters

Presentation Number

SS7-Header

Description 

SS7->SS7 

SS7->SIP 

ss7_pres_num_digits

Presentation Number

Y

Y

ss7_pres_num_nadi

Presentation Number Nature of Address Indicator

Y

Y

ss7_pres_num_screen_ind

Presentation Screen Indicator

Y

Y

ss7_pres_num_pres_ind

Presentation Indicator

Y

Y

ss7_pres_num_npi

Presentation Number indicating Plan Number

Y

Y

ss7_pres_num_pref_plan_ind

Presentation Number indicating preferenced plan

Y

Y


Link by Link National Forward Call Indicator

SS7-Header

Description 

SS7->SS7 

SS7->SIP 

ss7_fci_lxl_rci

Routing Control Indicator

Y

Y

ss7_fci_lxl_isi

Interconnect Specific Information

Y

Y


National Forward Call Indicator

SS7-Header

Description 

SS7->SS7 

SS7->SIP 

ss7_nfci_cli_blocking_ind

Call Indicator

Y

Y

ss7_nfci_nw_trans_addr_ind

Network Translated Address Indicator

Y

Y


Divert Line ID

SS7-Header

Description 

SS7->SS7 

SS7->SIP 

ss7_divertlineid_digits

Divert Line ID

Y

Y

ss7_divertlineid_nadi

Divert Line Nature of Address Indicator

Y

Y

ss7_divertlineid_screen_ind

Divert Line Screening Indicator

Y

Y

ss7_divertlineid_pres_ind

Divert Line Presentation Indicator

Y

Y

ss7_divertlineid_plan

Divert Line Plan

Y

Y

ss7_divertlineid_incomp_ind

Divert Line Incomplete Indicator

Y

Y

 

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