Before launching an outbound calling campaign, one critical question arises: are your phone numbers ready to perform? A thorough phone reputation audit can make the difference between a profitable campaign and a commercial disaster. Discover our complete 20-point checklist to ensure your numbers are in top shape.
Why audit your numbers before every campaign
A business phone number is more than just a technical identifier. It's your first point of contact with prospects, and its reputation directly determines your answer rates.
The true cost of a poorly-reputed number
The numbers speak for themselves: a number flagged as spam can see its answer rate drop by 60 to 70%. For a call center making 10,000 calls per day, that's up to 7,000 lost business opportunities daily.
Beyond unanswered calls, the consequences pile up:
- Wasted telecom costs: every unanswered call generates expenses with no return
- Declining agent productivity: time wasted on unsuccessful attempts
- Damaged brand image: being labeled as "spam" hurts your company's reputation
- Risk of permanent blacklisting: some carriers permanently block problematic numbers
To understand the full extent of these impacts, check out our detailed analysis on the hidden cost of a blacklisted number.
3 key moments to trigger an audit
Always trigger an audit in these situations:
- Before each new campaign: check your numbers' status 48 to 72 hours before launch
- When KPIs drop unexpectedly: if your answer rate drops by more than 15%, an audit is required
- After a period of inactivity: numbers dormant for more than 30 days need to be requalified
💡 Key takeaway: A preventive audit costs infinitely less than a failed campaign. Make it a mandatory step in your workflow.
Block 1: Technical checks (points 1-5)
Let's start with the technical fundamentals. These checks form the foundation of your audit and help detect structural issues.
1. Number status with your carrier
Action: Contact your telecom carrier to verify the administrative status of each number.
Points to check:
- Is the number still active and assigned to your organization?
- Are there any current restrictions or limitations?
- Has the number been flagged by the carrier?
- Are associated services (call forwarding, voicemail) properly configured?
2. STIR/SHAKEN configuration and attestation
Action: Verify the attestation level of your outbound calls.
The STIR/SHAKEN (Secure Telephone Identity Revisited / Signature-based Handling of Asserted information using toKENs) protocol authenticates call origins. Three attestation levels exist:
- Level A (Full): the carrier certifies the caller's complete identity - target to achieve
- Level B (Partial): the call origin is verified but not the authorization to use the number
- Level C (Gateway): the carrier cannot verify the original call source
A low attestation level significantly increases the risk of being blocked by destination carriers.
3. Presence in public anti-spam databases
Action: Query the main anti-spam databases.
Check if your numbers appear in:
- Community-based reporting databases (collaborative blocking platforms)
- Major carrier blacklists
- Reverse lookup directories with "spam" or "telemarketing" labels
Use a professional tool to instantly check your numbers' reputation across all these databases.
4. Reputation score on call blocking apps
Action: Test your numbers on the most popular call blocking applications.
Apps like Truecaller, Hiya, or carrier-specific apps assign reputation scores based on user reports. Check:
- The assigned score (typically 0-100 or color-coded)
- The number of reports received
- Associated comments and labels ("telemarketing", "scam", "survey"...)
- The trend: is the score improving or declining?
5. Caller ID display consistency
Action: Make test calls to different device types and carriers.
Verify that:
- The displayed number matches the configured number
- The company name displays correctly (if CNAM service is enabled)
- The display is consistent across mobile, landline, and VoIP applications
- No negative labels appear alongside the number
Block 2: Call metrics analysis (points 6-10)
Your call performance data reveals the true state of your phone reputation. Carefully analyze these phone reputation KPIs to track.
6. Answer rate over the last 30 days
Action: Calculate and analyze your overall and per-number answer rate.
Benchmarks to know:
- > 25%: Excellent - healthy number
- 15-25%: Acceptable - monitoring recommended
- 10-15%: Concerning - investigation needed
- < 10%: Critical - immediate action required
Compare these rates with your historical data to detect any abnormal degradation.
7. Average conversation duration
Action: Analyze the average duration of your connected calls.
A very short average duration (< 30 seconds) may indicate:
- Immediate hang-ups (poor perceived reputation)
- Unqualified contacts
- Spam identification upon answering
Compare by time slots and prospect segments to refine your diagnosis.
8. Inbound callback rate
Action: Measure the volume of callbacks generated by your outbound calls.
A healthy callback rate (between 5% and 15% of unanswered calls) indicates that your number inspires trust. A rate close to zero suggests recipients are deliberately avoiding calling back a number they perceive as unwanted.
9. User complaint volume
Action: Monitor complaints and reports received through all channels.
Centralize and analyze:
- Direct complaints to customer service
- Reports on anti-spam platforms
- Requests for removal from call lists
- Negative mentions on social media
A spike in reports should trigger an immediate response: pause calls on the affected number and conduct a thorough investigation.
10. Answer rate trends by carrier
Action: Segment your statistics by destination carrier.
Some carriers apply stricter filters than others. If you notice a sudden drop in answer rate on a specific carrier, this may indicate:
- Active blocking of your number by that carrier
- An update to filtering algorithms
- Concentrated reports from that carrier's subscribers
Block 3: Regulatory compliance (points 11-14)
Legal compliance is not optional. It protects your company from penalties and preserves your long-term reputation.
11. Do-Not-Call registry verification
Action: Confirm your registration as a professional on the Do-Not-Call registry and the compliance of your call files.
Under telemarketing regulations, you must:
- Be registered on the Do-Not-Call registry as a business user
- Scrub your prospecting files before each campaign
- Keep proof of scrubbing for 3 years
- Never contact numbers on the opt-out list
Penalties for non-compliance can reach significant fines depending on your jurisdiction.
12. Legal calling hours compliance
Action: Audit your campaign parameters regarding calling hours.
Regulations impose strict restrictions (varies by jurisdiction):
- Authorized days: typically weekdays only
- Authorized hours: usually between 8 AM and 9 PM local time
- Prohibited: weekends and public holidays in many regions
- Maximum frequency: limited attempts per month to the same number
Verify that your dialing systems automatically respect these constraints.
13. Consent traceability
Action: Audit your consent management system.
According to privacy regulations, individuals must have been informed and given the opportunity to object to the use of their data for telephone prospecting. Verify:
- Precise timestamp of each collected consent
- The channel and context of collection
- The exact wording presented to the prospect
- The ability to prove consent in case of audit
14. Up-to-date privacy documentation
Action: Review your privacy compliance documentation related to phone campaigns.
Your file should include:
- The processing register including telephone prospecting
- Information notices delivered to prospects
- Procedures for managing rights (access, rectification, objection)
- Impact assessment if you process sensitive data or on a large scale
Block 4: History and context (points 15-17)
A number's history directly influences its current reputation. Don't neglect this temporal dimension.
15. Number age and history
Action: Trace the complete history of each number in your pool.
Document:
- The date of acquisition or assignment of the number
- Call volumes issued month by month
- Campaigns the number participated in
- Past reputation incidents and their resolution
An old number with a clean history represents a valuable asset. Protect it.
16. Previous industry use (recycled numbers)
Action: Check if your numbers were previously used by other organizations.
Carriers regularly recycle numbers. A number can inherit a bad reputation from its previous user, especially if it was used for:
- Aggressive telemarketing
- Phone scams
- Negatively perceived sectors (debt collection, online gambling...)
Before integrating a new number, systematically test its pre-existing reputation.
17. Past incidents and resolutions
Action: Build an incident history for each number.
For each past incident, document:
- The nature of the problem (blocking, reports, performance drop)
- The detection date and incident duration
- Corrective actions implemented
- The reputation recovery timeframe
This history helps identify recurring patterns and anticipate future risks.
Block 5: Operational readiness (points 18-20)
A successful audit is not enough: prepare your organization to maintain this quality over time.
18. Number rotation and available pool
Action: Evaluate the diversity and availability of your number pool.
Best practices to verify:
- Numbers-to-agents ratio: have at least 3 numbers per active agent
- Geographic diversity: vary area codes if relevant
- Backup numbers: keep a reserve of unused numbers for emergencies
- Rotation policy: define clear rotation rules between numbers
19. Warm-up plan for new numbers
Action: Verify the existence and application of a warm-up protocol for new numbers.
A new number without history must be "warmed up" gradually:
- Week 1: volume limited to 20% of target capacity
- Week 2: increase to 40%
- Week 3: move to 70%
- Week 4: full capacity if metrics are satisfactory
For more on this crucial topic, check out our complete guide on warming up new phone numbers.
20. Real-time alerts and monitoring configured
Action: Validate the implementation of a continuous monitoring system.
Your monitoring system should include:
- Automatic alerts: immediate notification if a KPI crosses a critical threshold
- Real-time dashboards: instant visualization of each number's status
- Daily reports: automated summary of the previous day's performance
- Defined escalation: clear procedure for who to contact in case of an alert
💡 Key takeaway: Good monitoring detects problems before they impact your results. Invest in proactive surveillance tools.
Downloadable template: your audit checklist
To facilitate your regular audits, we provide a ready-to-use template.
Excel/Google Sheets version
Our template includes:
- All 20 checkpoints with checkboxes
- Automatic scoring cells
- A summary table with color coding (green/orange/red)
- History of previous audits for comparison
- Formulas for calculating key KPIs
How to adapt it to your organization
Customize the template according to your needs:
- Add your specific thresholds: adapt benchmarks to your industry
- Integrate your numbers: create a tab per number pool or per campaign
- Define responsibilities: assign each verification block to a team member
- Schedule audits: add an automatic recurrence calendar
- Connect your tools: if possible, automate data import from your systems
FAQ
How often should I run this audit?
The optimal frequency depends on your activity volume:
- High-volume call centers (> 50,000 calls/month): weekly audit recommended
- Medium activity (10,000-50,000 calls/month): bi-weekly audit
- Low volume (< 10,000 calls/month): monthly audit minimum
In all cases, perform a complete audit before each major new campaign.
How long does a complete audit take?
The time required varies depending on the size of your number pool:
- 1-10 numbers: 1 to 2 hours
- 10-50 numbers: half a day
- 50+ numbers: 1 to 2 days (consider automation)
Using automated tools can reduce these times by 70-80%.
What should I do if a number fails multiple checkpoints?
Follow this protocol based on the number of failing points:
- 1-3 minor points: fix the issues and continue using the number under enhanced monitoring
- 4-6 points or major issues: pause the number and launch a remediation plan
- 7+ points or confirmed blocking: remove the number from the active pool and assess whether it can be recovered or should be abandoned
Sources: CNIL - Telephone commercial prospecting, CNIL - GDPR compliance and consent
