SC-19: Voice Over Internet Protocol

To meet the sc-19: voice over internet protocol requirement, treat VoIP as a normal enterprise service that must inherit your baseline security controls, then prove it with ownership, documented procedures, and recurring evidence. Your fastest path is to scope every VoIP component (apps, phones, SBCs, carriers), map it to existing NIST SP 800-53 controls, and retain artifacts that show the controls operate.

Key takeaways:

• SC-19 does not create a separate “VoIP security program”; it expects you to secure VoIP with the same rigor as other protocols. ¹
• Audit success depends on evidence: clear control ownership, implementation steps, and repeatable artifacts tied to VoIP in scope. ¹
• Most gaps come from blind spots in scope (shadow VoIP apps, softphones, carrier-managed features) and missing operational proof.

SC-19 is a “technology-specific” control in NIST SP 800-53 that points you to a practical reality: VoIP is just another protocol and service stack you must secure. The control text is short, but it triggers real work for compliance teams because VoIP often lives across boundaries. Some pieces sit in traditional IT (network, identity, endpoint management), others sit with telecom teams, and others sit with third parties (UCaaS providers, SIP trunk carriers, managed contact centers).

For a CCO or GRC lead, the win condition is straightforward: you can show (1) what VoIP exists in your environment, (2) which baseline controls apply, (3) how those controls are implemented for VoIP, and (4) what evidence you retain to prove ongoing operation. SC-19 is commonly assessed indirectly through adjacent controls (boundary protection, encryption, configuration management, logging, incident response), so the operational approach is to map VoIP to your existing control system rather than invent a parallel one.

This page gives you requirement-level guidance you can execute quickly: scoping, ownership, minimum control expectations, artifacts, audit questions, and a practical execution plan.

Regulatory text

Excerpt: “Technology-specific; addressed as any other technology or protocol.” ¹

Plain-English interpretation

SC-19 tells you: if you run VoIP, secure it the same way you secure other enterprise protocols and services. The requirement is less about a special VoIP checklist and more about preventing VoIP from becoming an unmanaged exception.

What an operator must do:

• Identify VoIP services and components that handle organizational communications.
• Apply your existing security control baseline to those components (identity, network protections, encryption, logging, configuration, vendor management, etc.).
• Document “how” you did it and keep repeatable evidence that it stays in place.

If your VoIP is fully outsourced (for example, UCaaS), SC-19 still applies: you must manage the third party and configure the service securely, then keep proof.

Who SC-19 applies to

Entity scope

SC-19 is relevant for:

• Federal information systems
• Contractor systems handling federal data ¹

Operational scope (what to include)

Treat “VoIP” broadly so you don’t miss the assessed surface area:

• UCaaS platforms (calling, meetings, messaging) where voice traffic is carried over IP
• SIP trunks, session border controllers (SBCs), voice gateways
• Softphones and mobile VoIP clients
• Desk phones and conferencing devices on corporate networks
• Call recording, voicemail, transcription, and contact center integrations
• Admin consoles, APIs, and identity integrations (SSO, SCIM)

A common assessment failure is scoping VoIP as “the phone system” and missing softphones, meeting clients, and integrations that carry voice or call metadata.

What you actually need to do (step-by-step)

1) Set ownership and assessment boundaries

• Assign a control owner for SC-19 (often Network Security, Unified Communications, or Security Engineering).
• Assign supporting owners: IAM, Endpoint, SOC, Procurement/TPRM, and IT Ops.
• Define the system boundary: which networks, tenants, business units, and third parties are in scope.

Output: SC-19 control record with named owners and in-scope VoIP components.

2) Build a VoIP component inventory (the part auditors will test)

Create a list that is specific enough to verify:

• Service/provider name and tenant/account identifiers
• Major components (SBCs, gateways, clients, desk phones)
• Network segments/VLANs/SSIDs used by voice devices
• Admin roles and who holds them
• Integrations (SSO, call recording, CRM/contact center connectors)
• Data handled (voice media, call detail records, voicemail recordings)

Tip: If you already have CMDB/asset inventory, add VoIP as a tagged service with linked assets rather than building a separate spreadsheet.

3) Map VoIP to your existing NIST 800-53 control baseline

SC-19’s intent is “address as any other technology.” ¹ In practice, you map VoIP to the controls you already use for:

• Access control: SSO/MFA for admins, least privilege, role-based administration
• Network protections: segmentation for voice endpoints, SBC hardening, ingress/egress rules
• Encryption: encrypted signaling and media where supported by your architecture; encryption for stored call recordings and voicemails
• Configuration management: baseline configs for phones/clients/SBCs; controlled changes; secure defaults
• Logging/monitoring: admin actions, authentication events, configuration changes, call routing changes; forward to SIEM where feasible
• Incident response: playbooks for toll fraud, account takeover, eavesdropping indicators, compromised admin accounts
• Third-party risk: UCaaS/carrier security obligations, breach notification, subcontractors, data handling, and admin access constraints

Output: A control mapping matrix: “VoIP component → applicable controls → implementation method → evidence.”

4) Define minimum secure configuration standards for VoIP

Write a short VoIP security standard that points to enforceable settings:

• Identity: SSO enforced for admins; MFA required; break-glass accounts controlled
• Admin access: dedicated admin roles; admin actions logged; privileged access reviews
• Endpoints: managed device posture for softphones; desk phone provisioning locked down; disable unused services
• Network: voice device segmentation; restrict management interfaces; allow-list SIP peers as applicable
• Data: call recording retention rules; restricted access to recordings; secure sharing controls

Keep it tight. Examiners prefer standards that can be tested.

5) Operationalize recurring checks (so SC-19 stays true)

You need repeatable evidence. Build runbooks for:

• New VoIP site/tenant onboarding (security checks before go-live)
• Quarterly access reviews for VoIP admins and high-risk roles
• Change control for call routing, SBC rules, and recording settings
• Log review and alerting for suspicious events (admin logins, routing changes, unusual call patterns)

6) Close third-party gaps (UCaaS, SIP carriers, contact centers)

For each third party involved in voice:

• Confirm contract terms cover security responsibilities and incident notification.
• Verify your configuration responsibilities (SSO, MFA, logging exports, retention, role design).
• Document shared responsibility in your system security plan or equivalent control narrative.

If you use Daydream for third-party risk management, map the UCaaS and carrier to SC-19 and attach the same recurring artifacts you use for other critical third parties (ownership, review cadence, evidence checklist). Daydream’s value here is not a “VoIP module”; it is tight linkage between the requirement, owners, and evidence so assessments do not stall on documentation.

Required evidence and artifacts to retain

Auditors rarely “test SC-19” in isolation. They ask for proof that VoIP is not exempt. Retain:

• VoIP scope statement (what’s in scope, what’s excluded, and why)
• VoIP architecture diagram (high-level is fine) showing major components and trust boundaries
• Control mapping matrix tying VoIP components to your baseline controls
• Configuration standards (admin MFA/SSO requirement, segmentation standard, recording/retention rules)
• Screenshots or exports showing key settings (SSO enforced, MFA enabled, role assignments)
• Access review records for VoIP admin roles
• Change tickets for routing/SBC/recording configuration changes
• Log forwarding confirmation (SIEM ingestion evidence, sample events)
• Third-party artifacts: security addendum, shared responsibility notes, and your internal due diligence record

Common exam/audit questions and hangups

Expect these:

• “Show me your VoIP inventory and who owns it.”
• “How do you enforce MFA for VoIP administrative access?”
• “Where are call recordings stored, who can access them, and how is access reviewed?”
• “How do you prevent unauthorized call routing changes?”
• “What logs exist for VoIP admin activity and where do they go?”
• “Which third parties can administer your voice environment, and how do you control that?”

Hangups that slow assessments:

• No single diagram or boundary statement for VoIP
• Admin roles scattered across IT and telecom with no consolidated access review
• UCaaS treated as “vendor-managed,” with no proof of customer-side configuration

Frequent implementation mistakes (and how to avoid them)

1. Treating SC-19 as “N/A because we use a cloud phone provider.”
   Fix: document shared responsibility and retain proof of your controls in the tenant (SSO/MFA, roles, logging, retention).

2. Inventory stops at desk phones.
   Fix: include meeting clients, mobile apps, call recording, and integrations. If voice flows through it, scope it.

3. No evidence trail for voice configuration changes.
   Fix: route SBC/routing/recording setting changes through change management and keep tickets.

4. Overly long VoIP policy that nobody can test.
   Fix: write a short, testable standard with a checklist of required settings and artifacts.

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for SC-19. Practically, SC-19 gaps increase exposure to:

• Account takeover of voice admins (leading to call routing manipulation)
• Toll fraud and service abuse
• Unauthorized access to recordings and call metadata
• Eavesdropping risks if encryption and endpoint/network controls are weak

For federal environments and contractors, these risks commonly become audit findings because VoIP is easy to overlook while still being mission-critical.

Practical execution plan (30/60/90)

Use this as an operator’s plan; adjust to your change calendar and VoIP architecture.

First 30 days (stabilize scope and ownership)

• Name SC-19 owner and supporting owners; document RACI.
• Build VoIP inventory and identify all third parties involved.
• Draft the VoIP boundary statement and a simple architecture diagram.
• Create the control mapping matrix and identify evidence you already have versus gaps.

Days 31–60 (implement and document the minimum baseline)

• Enforce SSO and MFA for VoIP admin access where supported.
• Tighten admin roles and remove stale privileged accounts; run an access review.
• Publish a VoIP secure configuration standard (short, testable).
• Route voice configuration changes into change management.
• Confirm call recording storage, retention rules, and access restrictions.

Days 61–90 (make it repeatable and assessment-ready)

• Ensure logging is available for admin actions and forwarded/retained per your logging standard.
• Add VoIP checks to onboarding/offboarding and periodic access review workflows.
• Finalize third-party due diligence records and shared responsibility notes for UCaaS/carriers.
• Package an “SC-19 evidence binder” (digital folder) with a table of contents tied to your mapping matrix.

Frequently Asked Questions

Does SC-19 require specific VoIP encryption settings?

The SC-19 text provided does not prescribe specific technical settings; it says VoIP is addressed like any other protocol. ¹ Your job is to apply your baseline encryption and data protection expectations to VoIP components and retain evidence.

We only use UCaaS. Can we mark SC-19 as not applicable?

Usually no. You still configure and administer the UCaaS tenant, manage identities, roles, recordings, and logs, and oversee the third party. Document shared responsibility and keep proof of tenant-side controls.

What’s the minimum evidence set that satisfies most assessors?

A scoped inventory, an architecture diagram, a mapping of VoIP to your baseline controls, and recurring artifacts (admin access reviews, configuration standards, and change/log evidence). If you cannot show repeatability, assessors tend to treat the control as weakly implemented.

Who should own SC-19 in a typical organization?

Put primary ownership with the team that can enforce VoIP configuration and network controls (Unified Communications, Network Security, or Security Engineering). Keep IAM, SOC, and TPRM as named supporting owners because they hold key evidence.

How do we handle “shadow VoIP” like meeting apps that include calling?

Add discovery to your scope process: application inventory, SSO app catalog review, and network egress review for known voice services. Treat any app carrying voice traffic or storing recordings as in-scope and map it to the same baseline controls.

Where does Daydream fit if we already have technical controls in place?

Daydream helps most when you need assessment-ready traceability: SC-19 ownership, implementation procedure, and a recurring evidence checklist tied to the VoIP third parties and internal operators. That reduces the common failure mode for SC-19: “controls exist, but nobody can prove it.”

Footnotes

1. NIST SP 800-53 Rev. 5 OSCAL JSON