Voice Traffic Filter Overview
VTF Admin Guide – Spam Blocker Powered By Mutare
Voice Traffic Filter (VTF) is a configurable call filtering and network security application for your voice channel. When VTF is implemented, calls to the enterprise can be filtered through a series of analytic steps including a dynamic database of known spam, scam, and robocall numbers, STIR/SHAKEN scoring data, as well as an organization-specific set of rules applied to incoming calls.
Any flagged call can be immediately dropped or redirected by enterprise policy without ringing through, reducing disruption and protecting users and the voice network from potential criminal intrusions.
To get started, users receive an email invitation.
User Setup & MFA
Clicking the link in the invitation email takes the user to the registration page where they set their password.
After login, users are prompted to set up Multi-Factor Authentication (MFA):
- Scan the QR code using an authenticator app
- Enter the one-time code in the login page
- Complete login
If there are issues, users should contact their administrator.
Note: Existing Console users will not repeat registration when added to a new tenant—they will see it in the tenant dropdown.
The Console
The Console provides access to:
- Navigation menu
- Profile
- Tenant Picker
- Feedback
Your profile allows you to change time zone and language. You can switch tenants from the dropdown. The Feedback option lets users submit input directly.
Configuration
The Configuration page defines how VTF analyzes and acts on inbound calls.
Filter Modes
- FILTER CALLS – Actively applies actions based on analysis
- MONITOR ONLY – Allows all calls but shows what would have happened
Tip: Start deployments in MONITOR ONLY mode to understand traffic patterns before enforcing actions.
Analysis Priority Order
Incoming calls are analyzed in this order:
- Custom Rules
- STIR/SHAKEN
- Proprietary Dynamic Database (PDD)
Call Actions
For each filtering layer, actions can be configured:
- Allow – Call proceeds normally
- Drop – Call is terminated
- Route – Call is redirected
- CAPTCHA Drop – Challenge, then drop on failure
- CAPTCHA Route – Challenge, then route on failure
Custom Rules
Custom Rules define how calls are handled based on:
- Calling number
- Called number
If a match is found, the configured action is applied. If not, analysis continues to the next layer.
STIR/SHAKEN
VTF allows configuration of how STIR/SHAKEN data is handled.
- Data comes from SIP signaling
- Uses the “verstat” parameter for validation results
- Actions can be assigned for each validation outcome
Recommendation: Send TN-Validation-Failed calls to CAPTCHA and drop failures.
Proprietary Dynamic Database (PDD)
The PDD is a continuously updated defense against spam, scam, and vishing attacks.
- Uses global threat intelligence sources
- Checks incoming calls against multiple databases
- Applies configurable actions to flagged numbers
Tip: Start with a “do-no-harm” approach using CAPTCHA actions during early deployment.
CAPTCHA
Voice CAPTCHA helps distinguish bots from humans.
- Caller must enter random digits
Recommended settings:
- Digits: 2–3
- Seconds: 10
- Attempts: 2–3
Call Activity
Provides visibility into inbound traffic and filtering results.
Dashboard Features
- Filter by phone number or date range
- Show/hide visual charts
Visualizations
- Total calls (wanted vs unwanted)
- CAPTCHA success/failure
- Breakdown of unwanted calls by filtering layer
Call Details
Detailed records include:
- Action taken
- Analysis performed
- Expandable rows for full details
Breakdown of unwanted calls by:
- Custom Rules
- STIR/SHAKEN
- Proprietary Dynamic Database
Best Practices
- Review call data regularly during onboarding
- Look for traffic spikes and patterns
- Identify repeat offenders
- Adjust filtering rules before enabling aggressive actions
Support
For platform issues, contact support and include tenant name, ID, timeframe, and examples.
