Years of VoIP development
POWERFUL • SCALABLE • SECURE
SIP Server SDK for Windows VoIP and IP-PBX Development
VaxVoIP is a developer SDK—not a hosted or ready-made SIP server—for building branded Windows SIP server, IP-PBX, IVR, call-center and auto-dialer software. Evaluate it for 30 days with working sample source code and demo applications.
✓ Full SIP server development toolkit
✓ Multi-Core & Processor Support
✓ SIP threat detection and prevention
✓ Microsoft Windows Server and Desktop
Fully functional evaluation
Concurrent calls license
Server and Desktop support
SDK • WINDOWS • DEVELOPMENT
What Is a SIP Server SDK?
A SIP Server SDK is a software-development toolkit used to add SIP registration, call routing, media handling and PBX services to your own application. VaxVoIP supplies exported functions, events, documentation and sample projects so developers can build a commercial VoIP server while retaining control of the product interface, business rules and deployment.
SIP Server SDK for Windows
Develop for Microsoft Windows Server and Desktop using C#, VB.NET, Visual C++ or Delphi sample projects.
Build your own VoIP product
Create an IP-PBX, IVR, call center, auto dialer, registrar, proxy, conferencing or AI voice service.
Start with working source code
Download the 30-day trial and evaluate basic and advanced IP-PBX projects before integrating the SDK.
Secure and scalable SIP engine
Use multi-core processing and SIP threat-detection events to build reliable commercial server applications.
SDK • OR • READY-MADE SERVER
SIP Server SDK vs Ready-Made SIP Server Software
Choose the VaxVoIP SIP Server SDK when you need to develop and brand your own Windows VoIP application, control its source-level workflow, or embed SIP server functions into another product.
If you only need to install and administer an existing PBX without writing software, a ready-made SIP server is the more appropriate category. The VaxVoIP trial is intended for developers evaluating an SDK, not as a permanently free public SIP server.
Download the Windows SDK trial →DEVELOPER • TOOLKIT
What the evaluation includes
- 30-day SIP Server SDK trial for Windows
- Basic and advanced IP-PBX demo applications
- C#, VB.NET, Visual C++ and Delphi sample code
- Technical manuals and implementation guides
ADVANCED • SECURITY
Protect your SIP server from common VoIP threats
The SDK includes methods and events that help detect SIP scanning, flooding and brute-force activity. Your application can apply the required blocking and prevention policy while keeping control of the user experience and infrastructure.
View SIP security guide →
SIP Server SDK
VoIP Server & PBX
Scan Threat
Flood Threat
Brute Force Threat
FEATURES
Everything needed to build commercial SIP services
Use the SDK as the communication engine behind your own branded server, hosted platform or enterprise deployment.
Multi-core and multi-processor support
Distribute workloads across available CPU cores and processors for high-capacity VoIP communication.
Highly customizable solution
Build your own interface and business logic using exported functions, events, sample applications and technical manuals.
SIP server security
Detect SIP scan, flood and brute-force attacks and integrate your own mitigation workflow.
Efficient WAV file playback
Reuse compressed wave buffers to reduce repeated compression work and lower CPU processing load.
IP-PBX features
Implement transfer, music on hold, forwarding, voicemail, busy lamp and other PBX capabilities.
Call-center services
Create queues, ring groups, pickup groups, parking, barging, monitoring, coaching and auto dialer services.
Conference rooms
Add multiple calls to server-side conference rooms for multi-user voice and chat services.
DTMF detection
Detect INBAND, RTP RFC 2833 and SIP INFO tones for IVR and automated workflows.
NAT and firewall friendly
Support SIP client connectivity without requiring STUN, E-STUN or port forwarding.
Supported SIP clients and phones
Register and communicate with standards-based SIP phones, softphones and compatible devices.
BUILD • YOUR • PRODUCT
One engine for multiple communication solutions
IP-PBX
Extensions, registration, routing, forwarding, transfer, voicemail and presence.
IVR System
Prompts, DTMF collection, call flows, database access and external integration.
Auto Dialer
Build predictive, progressive or power-dialing systems for campaigns.
Call Center
Queues, agents, supervisors, monitoring, recording and performance workflows.
Registrar & Proxy
User registration, location services, SIP routing and gateway connectivity.
Conferencing
Server-side audio conferencing and real-time multi-user communication.
Call Recording
Save communication in standard WAV format or access real-time PCM audio.
SIPREC Client Support
Connect calls to SIPREC protocol-based recording servers for centralized session recording.
DEPLOYMENT • ARCHITECTURE
Deploy on-premises, in a data center or in your chosen cloud
Connect SIP clients, IP phones and web applications to your VaxVoIP-powered SIP server, then integrate PSTN gateways, upstream SIP services, databases and business systems.
View Architecture Documents
SIP Clients
Softphones, IP Phones & Web Clients
SIP Server SDK
VoIP Server & PBX
PSTN GatewayExternal telephony
SIP ServicesServers & providers
Data SystemsStorage & CRM
DEMO • APPLICATIONS
Evaluate real SIP server projects for 30 days
Download fully functional demo applications to understand basic and advanced IP-PBX development before integrating the SDK into your product.
IP-PBX Basic Demo
Start with registration, calling and essential PBX functionality.
Download DemoIP-PBX Advanced Demo
Explore advanced call handling, IVR, queues, monitoring and server workflows.
Download DemoDOCUMENTATION
Technical guidance from architecture to deployment
Technical Manual
Exported functions, events and SDK integration reference.
SIP Server Security
Threat detection and prevention implementation guidance.
SIP Server Performance
Load-testing information and performance considerations.
License Activation
Instructions for activating and managing your license key.
Client Registration
SIP registration process and server-side workflow.
Phone-to-Phone Calls
Call procedures between registered SIP clients.
PSTN/GSM Connectivity
Connect the server with telephony gateways and external networks.
ITSP Connectivity
Connect to SIP trunks and IP-telephony service providers.
SAMPLE • SOURCE • CODE
Start with working projects in your preferred development environment
Download any sample project and evaluate it with the fully functional 30-day trial. Review its ReadMe.txt file for setup instructions and use the technical manual for details about SDK functions, events and implementation workflows.
IP-PBX Basic
Visual C# .NETCreate SIP users, process registrations and handle basic calls in C#.
Visual Basic .NETBuild a straightforward VB.NET PBX with user and call-event handling.
Visual C++Integrate the SIP server component into a native Visual C++ application.
DelphiDevelop a compact Delphi PBX for SIP registration and call routing.
IP-PBX Advanced
Visual C# .NETExplore C# call queues, transfers and advanced PBX service workflows.
Visual Basic .NETImplement multi-user PBX controls and call-center events in VB.NET.
Visual C++Build a native high-control PBX application with advanced call handling.
DelphiCreate advanced Delphi telephony services with routing and transfer logic.
Auto Dialer & IVR
Visual C# .NETAutomate outbound C# calls with audio prompts and DTMF menu processing.
Visual Basic .NETBuild a VB.NET dialer and IVR that responds to caller keypad input.
DOWNLOAD • SIP • SDK
Download the 30-Day SIP Server SDK Trial for Windows
Evaluate the VaxVoIP SIP Server SDK for Windows with sample source code, demo applications and development documentation.
FREQUENTLY • ASKED • QUESTIONS
Answers before you start building
Find practical answers about SIP server development, deployment, licensing and evaluation.
How do I get a 30-day trial?
Download the SDK, a demo application or any sample source-code project and evaluate it for up to 30 days.
How do I develop a SIP server?
Begin with the supplied sample source code and demo applications, then use the technical manual for details about exported functions, events and implementation workflows.
How can I secure a SIP server built with the VaxVoIP SDK?
The SDK provides methods and events for detecting and mitigating SIP scanning, flooding and brute-force activity. Read the SIP server security guide and review the supplied security sample source code for implementation guidance.
Which audio codecs are supported?
The SIP Server SDK supports GSM, iLBC, G.711 u-law, G.711 a-law and G.729 audio codecs.
Which operating systems are supported?
The SIP Server SDK is designed for Microsoft Windows and supports Windows Server and Desktop versions.
Does the SDK support multi-core and multi-processor systems?
Yes. The SDK is optimized to use available CPU cores and distribute communication workloads across multi-core and multi-processor systems.
Is call recording supported?
Yes. Calls can be recorded in standard WAV format, and applications can also work with real-time audio data.
Can I connect it to other SIP servers and gateways?
Yes. The SDK can connect to compatible SIP servers, PSTN gateways, gatekeepers and telephony service providers. See the technical manual for implementation details.
Can I use the SDK to build call-center services?
Yes. You can develop dialing, reception, queuing, call transfer, call parking, call pickup, barging and silent-monitoring services.
Can I develop live call-coaching features?
Yes. You can build private coaching workflows in which supervisors guide agents in real time without the customer hearing the supervisor.
Is the SIP Server SDK source code available?
Yes. The SDK source code can be provided with user rights, and source-code training can also be arranged.
ANNUAL • COMMERCIAL • LICENSING
Unlimited concurrent calls
Licensing includes technical support, updates, new releases, maintenance and bug fixes during the license term.
One year
$4,680
USD · single service and serverContact SalesTwo years
$8,760
USD · single service and serverContact SalesThree years
$12,040
USD · single service and serverContact SalesBUILD • YOUR • OWN • SIP • SERVER
Ready to develop your next VoIP platform?
Evaluate the SDK, review the sample projects and discuss your licensing or integration requirements with the VaxVoIP team.