PBXware STIR/SHAKEN Call Filtering works in a way where it is expected from providers to complete the whole process of Caller ID verification and pass a parameter value in the P-Asserted-Identity SIP header which is by default named 'verstat'.
There are three options in the STIR/SHAKEN section that can be configured per Tenant Level:
Set this field to a desired value
NOTE: This parameter is parsed for the caller ID validation and it is generally named 'verstat'. Other variations depend on the Trunk provider.
Enable PBXware STIR/SHAKEN Call Filtering
Select for which verification status calls will be dropped
The PAI header value will be parsed and if the given parameter is set and contains any of the selected values from the 'Drop Calls with Verification status' list, the call will be dropped.
Please refer to the list of verification statuses:
NOTE: Please note that verification statuses are case insensitive which means that all three of the following options are acceptable: ‘No-TN-Validation’, ‘NO-TN-VALIDATION’, and ‘No-tn-Validation’.
This will only work for calls from Trunks.
INFO: For more on the 'Pass PAI Header to UAD' option, please refer to HOWTO Configure STIR/SHAKEN with Polycom Devices.
Example: "P-Asserted-Identity: <sip:+1234567890;verstat=TN-Validation-Passed@xx.xxx.x.xxx:xxxx>
Please note that the additional header check is added for STIR/SHAKEN. 'P-Asserted-Identity' can have one of the following values: 'TN-Validation-Passed', 'TN-Validation-Failed', or 'No-TN-Validation', while the level can be seen in a new header, for example: 'P-Attestation-Indicator: B'.
In case a user selects 'TN-Validation-Failed-B' and 'No-TN-Validation' as values for 'Drop Calls with Verification Status', the call will be dropped as it matches 'TN-Validation-Passed' plus 'B'.
However, if there is no indicator provided, an exact match of the verstat value in the PAI header and the value specified in the 'Drop Calls with Verification Status' field is expected: "P-Asserted-Identity: <sip:+1234567890;verstat=TN-Validation-Passed-B@xx.xxx.x.xxx:xxxx>".