1. TN-PoP Scenarios
Jim McEachern
Principal Technologist
ATIS
August 2018

2. SHAKEN Attestation … ATIS-1000074 states:
Signing provider is asserting that their customer can “legitimately” use the number that appears as the calling party
Ultimately it is up to service provider policy to decide what constitutes “legitimate right to assert a telephone number”.
Analytics
SHAKEN
STI AS
STI VS …
SP-B
SP-C
SP-D
SP-Z

3. TN Proof of Possession (TN-PoP)
TN-PoP offers one mechanism service providers can use to confirm “legitimate right to assert a telephone number”.
The legitimate right to assert a telephone number is verified, in-band, as part of the signaling for each call.
SP-A
Analytics
SHAKEN
PoP AS
PoP VS
STI AS
STI VS …
SP-B
SP-C
SP-D
SP-Z

4. Other Mechanisms to Confirm “Right to Assert”
Service provider could maintain a white list of numbers the enterprise is entitled to use.
Every call would be checked against the white list to determine if it qualified for “full attestation”.
Analytics
SHAKEN
STI AS
STI VS
White List …
SP-B
SP-C
SP-D
SP-Z
Challenge: How to populate and maintain the white list in a cost effective and secure manner?

5. Other Mechanisms to Confirm “Right to Assert”
Service provider could install an application in the enterprise.
The application would use the TN-PoP mechanism to “prove” the enterprise had the right to use the number.
White list could be updated as required.
Verification could be conducted on a regular schedule specified by the service provider.
SP-A
Analytics
SHAKEN
PoP AS
App
PoP AS
App
STI AS
STI VS
White List …
SP-B
SP-C
SP-D
SP-Z
Benefits:
Would not require upgrade to enterprise PBX
Significantly simpler functionality & lower cost

6. Summary This approach would use standard TN-PoP framework.
The verification mechanism could use a standard SIP call setup conducted out- of-band between the application in the enterprise and the service provider.
All of this would effectively occur within a single service provider network, and therefore does not need to be standardized.
It would leverage standard TN-PoP mechanisms to obtain TN-PoP certificates
This contribution is for information only.