Transparent, Gateway-Scale Licensing
Select the tier that aligns with your concurrent channel requirements. Protect your operation with our enterprise-grade screening solution.
Call Filter Basic
Entry-level Call Filter package for small GSM termination operations, single gateway ...
- 16 Channel Maximum
- A+B Number Whitelist Filtering
- Dynamic Blacklist Management
- Real-Time CDR Analysis
- Test Call Blocking (99%+)
- Per-SIM Whitelist Binding
- Prefix & Suffix Rule Engine
- 24 Hours Free Trial
- Gateway Support: GoIP, DINSTAR
- Softswitch: VOS3000, Asterisk
Call Filter Professional
Professional Call Filter plan for medium-scale GSM termination, multi-gateway operati...
- 32 Channel Maximum
- A+B Number Whitelist Filtering
- Dynamic Blacklist Management
- Real-Time CDR Analysis
- Test Call Blocking (99%+)
- Per-SIM Whitelist Binding
- Prefix & Suffix Rule Engine
- 24 Hours Free Trial
- IVR DTMF Authentication
- HLR & Messenger Verification
- Priority Technical Support
Call Filter Enterprise
Enterprise-grade Call Filter solution for large-scale GSM termination farms, wholesal...
- 64 Channel Maximum
- A+B Number Whitelist Filtering
- Dynamic Blacklist Management
- Real-Time CDR Analysis
- Test Call Blocking (99%+)
- Per-SIM Whitelist Binding
- Prefix & Suffix Rule Engine
- 24 Hours Free Trial
- IVR DTMF Authentication
- HLR & Messenger Verification
- Custom Rule Configuration
- Dedicated Account Manager
- Community Threat Intelligence
Need More Than 64 Channels or Custom Rules? Contact us for a Custom Enterprise Quote.
The Test Call Threat to GSM Termination
Understanding the sophisticated detection methods deployed by operators is essential for building effective protection.
How Anti-Fraud Works
Mobile operators worldwide deploy increasingly sophisticated fraud systems to detect and block SIM cards. Anti-fraud companies build extensive networks to inject test calls through multiple channels: VoIP retailers, calling card services, and wholesale carriers.
When these known test numbers dial through your route and connect, the anti-fraud system immediately records the SIM's IMSI, IMEI, and BTS location. This data triggers rapid blocking. Furthermore, advanced anti-fraud systems use "poisoned" whitelists, generating test calls that appear to originate from trusted, legitimate sources.
The Devastating Impact
- Rapid SIM Blocking: In aggressive markets, unprotected SIMs last only 24-72 hours.
- Mass Gateway Blocking: Detection leads to mass blocking of all SIMs sharing the same IMEI or BTS location.
- Route Instability: Frequent blocking causes downtime, damaging your reputation with wholesale clients.
- ASR/ACD Degradation: Zero-duration test calls artificially deflate your metrics.
Call Filter vs Basic Protection
See why standard hardware routing rules fail against modern anti-fraud systems, and how Call Filter bridges the gap.
Technical Architecture & Filtering Flow
Call Filter processes every single SIP INVITE through a strict, zero-trust hierarchical pipeline before it ever touches your gateway hardware.
Pre-Call Verification
Checks A-Number (Caller ID) and B-Number (Destination) against trusted historical databases. If the A+B combination doesn't exist in legitimate traffic patterns, it is flagged.
Dynamic Blacklisting
Detects repetitive calling patterns, low-ASR numbers, short-duration calls (<5 seconds), and numbers with CLI patterns matching known test call signatures.
Authentication Layer
Suspicious calls are challenged via IVR DTMF prompts ("Press 1 to continue"). Additionally, HLR lookups and WhatsApp/Viber presence checks verify human legitimacy.
Post-Call Learning
CDR analysis evaluates call duration. Successful calls with good ACD automatically add the A+B pair to the whitelist, expanding the trusted database dynamically.
Filtering Capabilities
- Whitelist Types: A-number, B-number, A+B combination, Per-SIM, Prefix-based
- Blacklist Types: Static, Dynamic, Prefix-based, Suffix-based, Regex patterns
- Authentication Methods: IVR DTMF, HLR lookup, Messenger verification (WhatsApp/Viber/Telegram)
- Dynamic Detection: ASR/ACD analysis, repetitive pattern detection, duration-based filtering
- Processing Latency: < 50ms per call (whitelist/blacklist), < 200ms with HLR
- Test Call Blocking Rate: 99%+ with properly configured A+B filtering
Integration & Scale
- Softswitch Compatibility: VOS3000, Asterisk, FreePBX, StarTrinity, Custom SIP platforms
- Database Support: MySQL, MSSQL, PostgreSQL, ODBC, MongoDB
- API Integration: REST API, SOAP, Webhooks, CallXML, SIP header manipulation
- Max Calls Per Second: 100+ CPS (scalable with clustering)
- Rule Engine: Time-based, originator-based, destination-based, SIM-specific
- Reporting: Real-time dashboard, CDR export, blocking analytics, threat alerts
Who Benefits from Call Filter?
Call Filter is engineered to serve the most demanding telecommunication scenarios, from independent GSM termination to large-scale wholesale carrier routing.
GSM Termination Operators
Protect your SIM investment and maximize gateway uptime with intelligent call filtering for multi-gateway operations.
VoIP Wholesale Carriers
Offer clean, filtered traffic to your termination partners and build reputation as a trusted traffic source.
Anti-Fraud Service Providers
Integrate advanced filtering into your softswitch or gateway product to offer value-added protection to clients.
International VoIP Resellers
Build stable termination routes to high-demand destinations with proven anti-blocking protection.
Frequently Asked Questions
Detailed answers regarding the implementation, configuration, and capabilities of the Call Filter Anti-Blocking suite.
What is Call Filter and how does it prevent SIM blocking?
Call Filter is an advanced call screening solution that prevents test calls from anti-fraud companies from reaching your GSM gateway SIM cards. It uses A+B number whitelist filtering, dynamic blacklists, IVR DTMF authentication, and HLR verification to block 99%+ of test calls before they can trigger SIM blocking by mobile operators.
How does A+B number filtering work in Call Filter?
A+B number filtering verifies both the caller ID (A-number) and the called number (B-number) against a trusted database before allowing the call to reach your SIM card. Anti-fraud test calls use number combinations that do not exist in legitimate traffic patterns, making them easy to identify and block. This is the most effective anti-blocking method available.
What is dynamic blacklist management?
Dynamic blacklists automatically identify and block numbers exhibiting suspicious patterns such as repetitive calling with low ASR, short call durations, or unusual calling frequencies. The system learns from traffic patterns and continuously updates blacklists without manual intervention, adapting to new anti-fraud tactics in real-time.
How does IVR DTMF authentication block test calls?
IVR authentication requires incoming callers to press a specific DTMF digit (e.g., "Press 1 to continue") before the call connects to your SIM card. Anti-fraud test systems and robocalls typically cannot respond to IVR prompts, while real human callers can. This simple but highly effective filter blocks the majority of automated test calls.
Which gateways and softswitches are compatible with Call Filter?
Call Filter supports all major SIP-based GSM gateways including GoIP (all models), DINSTAR (all models), Skyline, IQSIM, TELES, Antrax, Hybertone, and Ejoin. It also works seamlessly with softswitches like VOS3000, Asterisk, FreePBX, StarTrinity, and custom SIP platforms. It operates as a pre-filter layer before calls reach your termination infrastructure.
What is included in the 24-hour free trial?
The 24-hour free trial includes full access to your selected Call Filter package with all features enabled. You receive whitelist/blacklist configuration, dynamic filtering, CDR analysis, and full technical support during the trial period. No credit card is required. Our team will configure your test environment and help you build your initial whitelist from your traffic patterns.
Can Call Filter work alongside other VPN Worlds solutions?
Yes, Call Filter is designed to integrate seamlessly with VPN Worlds ViBE, VPN4GW, and SimPro solutions. Many clients use Call Filter as the first line of defense (blocking test calls), SimPro for human behavior simulation and IMEI rotation, and VPN4GW for encrypted tunnel connectivity — creating a comprehensive multi-layered anti-blocking strategy.
What payment methods and billing cycles are available?
We accept all major credit and debit cards, PayPal, bank wire transfers, and cryptocurrency payments (Bitcoin, USDT). For enterprise clients, we offer monthly, quarterly, and annual billing cycles with discounts for longer commitments. Post-paid contracts are available for established partners with verified credit history.
Stop Replacing Blocked SIMs Today
Every hour without Call Filter is another test call compromising your infrastructure. Deploy the industry's most robust call filtering solution and watch your termination profitability soar.
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