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VoIP Softphone SDK

Access our core libraries to create customized IMS-compliant solutions

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Home»Products»Developer Tools»Softphone SDK

VoIP Softphone SDK


The VoIP Softphone SDK offers access to CounterPath core softphone libraries, enabling engineers with comprehensive VoIP experience to develop complex applications that facilitate IMS-compliant voice and video calling, as well as instant messaging and presence capabilities. Application developers can also use the SDK to build their own graphical user interface and implement calling behaviors for features such as call answer, call transfer, conferencing and more.

The core SDK uses C++, with wrappers available for different programming environments, such as .NET, Java, Objective-C, Swift and Xamarin. Through the use of a common SDK, developers can leverage the same set of core methods/parameters regardless of the underlying operating system, gaining significant IOT benefit from the use of the same signaling stack, media stack, etc. across all platforms.

Included with the purchase of the Softphone SDK is a Developer Guide, sample application code and dedicated email support to ensure success in deploying SDK developed applications.

New to SDK 1.9

  • Linux SDK Support
    Create a VoIP calling application, or integrate voice calling within your Linux-based application, with the latest version of CounterPath's Softphone SDK.
  • 64-bit Android Support
    With the Google Play Store requiring 64-bit support for all Android applications published after August 1, 2019, CounterPath has proactively released 64-bit support in our SDK so application developers can implement prior to this date.
  • SDK Push Notification Documentation and Samples
    There is now a dedicated new section of developer guide for SIP push, sequence diagrams, Stretto HTTP API documentation


  • Leverages CounterPath’s market leadership, earned from deploying tens of millions of SIP softphone clients.
  • Best-in-class voice quality with stellar audio test results.
  • Proven operability with a wide range of SIP-based network equipment including Cisco, Avaya, Microsoft, Ericsson, ALU, NSN, Huawei, BroadSoft, GENBAND, Metaswitch, Mavenir, Genesys, Digium / Asterisk, Mitel, Panasonic and others.
  • Support for multiple programming environments – core SDK uses C++, with wrappers available for .NET, Java, Objective-C, Swift and Xamarin.
  • Multi-platform support – CounterPath’s Softphone SDK is supported on Windows and Mac desktop as well as Android and iOS mobile platforms.
  • Product support and sample application included to help get developers quickly up to speed in designing and deploying their application.


CounterPath's Softphone SDK is a SIP C++ SDK, with wrappers available for .NET, Java, Objective-C, Swift and Xamarin. Documentation and support is available in English only at this time.

Telephony Features

  • Enhanced Voice Quality
    • Includes support for a broad range of Voice Quality Enhancement (VQE) capabilities, such as:
      • Acoustic Echo Cancellation
      • Adaptive Jitter Buffer
      • Packet Loss Concealment
      • Noise Reduction
  • HD voice calls with support for a range of voice codecs including G.722, SILK, OPUS, G.711 and G.729
  • Up to 1080p HD video calling with support for H.264 and VP8 video codecs
  • Support for call features including call transfer, call waiting, hold and mute
  • Local conferencing/three-way calling
  • Calling Line Identity Presentation (CLIP) aka. Call Display
  • Calling Line Identity Restriction (CLIR) aka. Call Display Block
  • Dial plan normalization
  • Voicemail support with Message Waiting Indicator (MWI)
  • CallKit support for native call integration with iOS 11+

Instant Messaging and Presence Features

  • SIP SIMPLE and XMPP support
  • IM can be used for sending SIP-based text message to an SMS gateway, where they can be converted to SMS format and sent to a mobile network

Security Features

  • Support for TLS and SRTP for advanced signaling and media encryption
  • 256-cryptographic support for SRTP

IMS Compliance Features

  • Support for IMS capabilities such as REGEVENT

Device Management Features

  • Support for device querying and switching between devices, however the control logic for detecting when a new device is plugged in is handled outside of the SDK

Call Quality Statistic Features

  • Includes support for querying RTCP-based call information, including latency, packet loss and more, for both video and voice calls

Enhanced Stretto™ Management Tools

  • Integration of the Stretto Platform Provisioning Module enables application developers with the ability to leverage Stretto to easily retrieve or manage SIP account and related settings. CounterPath’s Softphone SDK also supports User Experience Metrics (UEM) Module to add analytics and Voice Quality Monitoring (VQM) data collection for desktop clients. UEM provides administrators with valuable insight into end user behaviors and experiences with their Bria client, such as service quality, device usage, and feature usage.

Dedicated Support

When creating applications within tight deadlines, developers cannot afford to wait for weeks for trouble tickets to be resolved. CounterPath’s Softphone SDK Extended Support plan includes direct email access to dedicated Engineering resources, as well as SLA-based trouble ticket response time guarantees.


Restrictions and Limitations

Please note that the following capabilities are expected to be handled at the application layer:

  • Contact management
  • Multiple account support
  • Call logs
  • Higher level telephony features such as auto-answer, emergency calling and voicemail retrieval
  • Provisioning*
  • Data persistence

* I.e. the application will typically need to obtain configuration data from the provisioning user; for this reason, the application is responsible for pushing the configuration data to the SDK


The requirements for hardware and system are heavily dependent on the type of application being created by the Softphone SDK. At minimum, CounterPath recommends the following:

Development Environment

Language C++
C++ C++
.NET (with Xamarin)
.NET (with Xamarin)
Operating System Microsoft Windows 7 SP1 and above macOS 10.13 and above CentOS 7 macOS 10.13 and above Microsoft Windows 7 SP1 and above Microsoft Windows 7 SP1 and above
Memory Minimum: 4 GB
Optimal: 8 GB
Minimum: 4 GB
Optimal: 8 GB
Minimum: 2 GB
Optimal: 4 GB
Minimum: 4 GB
Optimal: 8 GB
Minimum: 4 GB
Optimal: 8 GB
Minimum: 4 GB
Optimal: 8 GB
Hard Disk 2 GB 2 GB 2 GB 2 GB 2 GB 2 GB
Framework and SDK .NET 3.0   devtoolset-6  iOS 10 SDK or later JDK 7 or later
Android SDK 26 or later
Development Software Windows Visual Studio 2015 Mac XCode 10 or later   Mac XCode 10 or later Android Studio 3.0 Visual Studio for Mac 7.4 or later, Xcode 10 or later
Processor Intel Core i5 Intel Core i3 Intel Core i3 Intel Core i3 Intel Core i5 Intel Core i5

Runtime Environment

Operating System Microsoft Windows 7 SP1 and above Mac OS X 10.13 and above CentOS 7 iOS 11+ 5.0 and above iOS 10 and above or Android 5.0 and above
Target i386 and x64 (via WOW64, Microsoft's compatibility layer). x86_64 x86_64 x86_64
x86 via libhoudini*

* only on supported devices listed below
For iOS: x86_64, armv7, arm64

For Android: armeabi, armeabi-v7a, arm64, x86 via libhoudini
Supported Devices       Please see Bria Mobile for iOS Please see Requirements > Supported Devices for a full list: Bria Mobile for Android  


To inquire about Softphone SDK, please complete and submit the Sales Request Form and a CounterPath sales representative will contact you with more information.


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