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Softphone SDK

Access our core libraries to create customized IMS-compliant solutions

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Home»Products»Developer Tools»Softphone SDK

Softphone SDK


The Softphone SDK offers access to CounterPath’s 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 1.8

  • Support for mutual TLS authentication with SIP
    The Softphone SDK can now be used in high security environments where mutual authentication is enabled, and future-proofed when it becomes mandatory.
  • iOS 64-bit Simulator Support
    Instead of switching to a 32-bit build to run simulations when developing applications, developers can remain in 64-bit mode and make calls with the simulator, reducing time and frustration when creating applications in 64-bit mode.
  • Support for Dynamic Framework Bundles with iOS Apps
    Apps using the SDK have better flexibility by not having to compile in the SDK with the app, and also better their load time and memory performance by delay loading the SDK.
  • SIP OPTIONS Ping Support
    When supported by a call server, Softphone SDK built apps now have better connectivity monitoring without heavy SIP re-registers. Please see the SDK 1.8 Release Notes for details.
  • Ability to Create Multiple Instances of CPCPhone on Mac and iOS
    Multiple instances of the Softphone SDK can now be run simultaneously doing different tasks for increased flexibility in developing custom solutions for Mac and iOS.
  • XMPP File Transfer Improvements
    The file transfer features of XMPP have been updated to be more resilient, including fixes to prevent crashes and improved APIs for file transfers with XMPP.


  • 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, AMR-Wideband, 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 10+

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++
.NET (with Xamarin)
.NET (with Xamarin)
Operating System Microsoft Windows 7 and above macOS 10.13 and above macOS 10.13 and above Microsoft Windows 7 and above
Memory Minimum: 4 GB
Optimal: 8 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
Framework and SDK .NET 3.0   iOS 10 SDK or later JDK 7 or later
Android SDK 23 or later
Development Software Windows Visual Studio 2015 Mac XCode 8 Mac XCode 8 Android Studio 2.3
Processor Intel Core i5 Intel Core i3 Intel Core i3 Intel Core i5


  • Language: C++, .NET
  • Operating System: Microsoft Windows 7 and above
  • Memory: Minimum: 4 GB / Optimal: 8 GB
  • Hard Disk: 2 GB
  • Framework and SDK: .NET 3.0
  • Development Software: Windows Visual Studio 2012
  • Processor: Intel Core i5


  • Language: Objective-C
  • Operating System: macOS 10.12 and above
  • Memory: Minimum: 4 GB / Optimal: 8 GB
  • Hard Disk: 2 GB
  • Development Software: Mac xCode 6.1
  • Processor: Intel Core i3


  • Language: C++, Objective-C
  • Operating System: macOS 10.12 and above
  • Memory: Minimum: 4 GB / Optimal: 8 GB
  • Hard Disk: 2 GB
  • Framework and SDK: iOS 7 SDK
  • Development Software: Mac xCode 6.1
  • Processor: Intel Core i3


  • Language: Java
  • Operating System: Microsoft Windows 7 and above
  • Memory: Minimum: 4 GB / Optimal: 8 GB
  • Hard Disk: 2 GB
  • Framework and SDK: JDK 6 or later, Android SDK 22.3
  • Development Software: Android Studio 1.0.0
  • Processor: Intel Core i5

Runtime Environment

Operating System Microsoft Windows 7 and above macOS 10.12 and above iOS 10 or 11 5.0 (API Level 21) and above
Target i386 and x64 (via WOW64, Microsoft's compatibility layer). x64    armeabi*

*only on supported devices listed below
Supported Devices     iPhone 4 and above
iPad 2 and above
Please see Requirements > Supported 
Devices for
a full list: Bria Mobile for Android


  • Operating System: Microsoft Windows 7 and above
  • Target: i386


  • Operating System: macOS 10.12 and above
  • Target: x64


  • Operating System: iOS 10 and above
  • Target: iPhone 4 and above, iPad 2 and above


  • Operating System: 4.4 (API 19) and above
  • Target: armeabi, armeabi-v7a


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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