---
name: framework-financial-services-controls-sc-7.4
title: SC-7 (4) -  External Telecommunications Services
description: Implement a managed interface for each external telecommunication service.
last-updated: 2026-08-26
---

> ## Documentation Index
> The table of contents for this documentation set is at https://cloud.ibm.com/docs/framework-financial-services-controls?format=markdown
> The index for all IBM Cloud docs is at: https://cloud.ibm.com/docs/llms.txt
> Use these files to discover more information as needed.

# SC-7 (4) -  External Telecommunications Services
{: #sc-7.4}

## Control requirements
{: #control-requirements}



### SC-7 (4) (a)
{: #sc-7-4-a}


Implement a managed interface for each external telecommunication service.


### SC-7 (4) (b)
{: #sc-7-4-b}


Establish a traffic flow policy for each managed interface.


### SC-7 (4) (c)
{: #sc-7-4-c}


Protect the confidentiality and integrity of the information being transmitted across each interface.


### SC-7 (4) (d)
{: #sc-7-4-d}


Document each exception to the traffic flow policy with a supporting mission or business need and duration of that need.


### SC-7 (4) (e)
{: #sc-7-4-e}


Review exceptions to the traffic flow policy _[IBM Assignment: at least annually]_ and remove exceptions that are no longer supported by an explicit mission or business need.


### SC-7 (4) (f)
{: #sc-7-4-f}


Prevent unauthorized exchange of control plane traffic with external networks.


### SC-7 (4) (g)
{: #sc-7-4-g}


Publish information to enable remote networks to detect unauthorized control plane traffic from internal networks.


### SC-7 (4) (h)
{: #sc-7-4-h}


Filter unauthorized control plane traffic from external networks.












## NIST supplemental guidance
{: #nist-supplemental-guidance}

External telecommunications services can provide data and/or voice communications services. Examples of control plane traffic include routing, Domain Name System (DNS), and management. Unauthorized control plane traffic can occur through a technique known as “spoofing.”