M4 SBC: Class 4 Softswitch


M4 SBC is a Class 4 Softswitch dedicated to managing VoIP wholesale business.
It is easy to use, powerful and all-in-one solution for wholesale providers who want to get the daily job done fast.

Softswitch Class 4

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Who is this system designed for?

For VoIP wholesale business:

Wholesale Termination

DID Forwarding

SIP Trunking

GSM Termination


Carrier Grade M4 SBC platform with it's rich functionality enables service providers to run VoIP wholesale business operations with ease


  • Support real-time billing, prepaid and postpaid
  • Real-time balance update: live calls are dropped if balance is out of credit
  • Multicurrency support (Manual or automatic exchange rate)
  • Force cut off
  • Loop detection mechanism
  • Online and aggregated CDRs
  • VAT accounting
  • Comprehensive financial analysis
  • Notification system
  • Integrated automated, customizable invoicing system
  • Price list/Tariff management
  • Import/export of price lists from/to CSV files
  • Pricelist generator for originators (customers): compare and analyze pricelists of terminators (suppliers), apply margins, generate new price list
  • Configurable billing patterns for call rating
  • Configurable rounding method (round/up/down)
  • Time zones can be configured on individual Vendor or Client basis
  • Low balance notification by email


  • Routing by LCR (Least Cost Routing)
  • Routing by Priority (Forced/preference routing)
  • Routing by Preset Proportion (Percentage based routing)
  • Routing by Quality (Adaptive Routing based on ASR/ACD formula)
  • Routing by CallerID (Origination based routing, EU requirement))
  • Originator authentication based on IP address, Tech. prefix
  • Traffic failover
  • Load balancing/sharing for termination endpoints
  • Multiple routing plans
  • Automatic blockage of unprofitable calls (Profit/loss protection)
  • Lines limits for originators and terminators
  • Maximum call time limitation
  • Unlimited Supplier (Vendor/Provider) Connections
  • The dialed number and CLI manipulation. Normalization of number format
  • Blacklists, white lists
  • Custom processing of SIP Headers
  • Test Dialplan tool – Call routing simulator/debugger
  • The route to client PBXs by IP addresses – Trunking


  • Signaling Protocol: SIP
  • Network Protocols: TCP, UDP, RTP, RTCP
  • Audio codec support: G.711 (a/u), G.723.1 (passthrough only), G.729a, G.726, GSM, G.722, Speex (8kHz using 20ms ptime), OPUS
  • Codec Transcoding
  • Fax support: T.38 Fax Relay Protocol
  • Specify audio codec and priority per connection point

Reporting / Troubleshooting

  • PCAP/RTP trace
  • Traffic reporting for calls
  • Charts reports for concurrent calls, call duration, and ASR
  • Sales reports for payments, cost, and revenue
  • Users reports with full CDR
  • Statistical reports based on routes, clients, providers, time, etc
  • Export to .pdf or .csv formats
  • Flexible Summary/Aggregate reports
  • Sales, Payments Reports
  • PDF Invoice export
  • Profit/Loss Reports
  • Reports by Call Hangup Cause, Destinations

Invoicing / Balance Management

  • Per-customer invoice templates, including logo
  • Multiple billing increments
  • Credit limit and prepayment management
  • Balance and payments management
  • Contact management
  • Automatic and batch invoicing
  • Exportable carrier, balance and invoice reports

Real-Time Monitoring

  • Active Calls (Connected/Ringing)
  • Softswitch status
  • User Activity
  • Detailed SIP logs
  • Real-Time Alerts for various situations
  • CPU/RAM utilization, hard disk real-time monitoring
  • Services monitoring
  • Dynamic Provider Quality Deviations from baseline Provider


  • IP blocking on failed attempts to register, login, etc
  • IP blocking by Country
  • Built-in high-performance IP firewall
  • Password security controls
  • User Audit Logging
  • Support setting different authority for different users
  • Login uses SHA512, RSA2048 encryption
  • Protection against Brute-force attacks
  • SSH Blacklisting

Support & Updates

  • 24×7 Rapid response ticketing portal
  • Remote monitoring
  • Ticket escalation
  • Entitled to all maintenance releases and major version upgrades
  • The in-house Development team for product refinement and extra development
  • Remote Support through Secured SSH access.
  • Interactive training sessions for all new customers using screen sharing
  • Installation and Provisioning support


System Administration

  • Network Activity Recorder for analysis and debugging purposes
  • Re-rate CDR tool
  • Destination/Prefix management
  • Access Controls for Web users.
  • Complete control Web Interface

XML-based API Integration

  • API for integration with third-party ERP, CRM, CMS, OSS/BSS software
  • Develop Custom solutions and integrations
  • Language agnostic – use any language of choice: Python, Java, PHP, Ruby, etc.
  • Manipulate Accounts, Customers and Vendors
  • Full documentation available for all API methods

What does it look like?

Here you can check various screenshots from the M4 GUI

Testing Options

Kolmisoft offers many ways to try M4. Click here to learn about the testing options.