FAQ (25)

I like your SDK. How to buy your license?

Use our order form with desired support period. Our sales manager will provide you with a price quote and link to buy the license.

How to call on the application?

SDK implements SIP client functionality.
It can make direct calls between 2 apps, but typically is required to use SIP server/PBX.
Search in SIP providers in your region, create account(s), enter received credentials in app and make calls.
See also here:

Which credentials should I enter on registration screen?

How to collect log information on Windows?

To detect most detailed log level:

  • 1. Set on initialization stage
    phone.Config.LogLevel= (LogLevelType)11;
    phone.Config.LogPath = "C:\\temp\\logs";//own path to existing folder
  • 2. Build app, run
  • 3. Send us all *.txt files created by SDK in ‘LogPath’ folder.
    Default path, where SDK creates log files is
     x86 SDK: C:\Users\Admin\AppData\Local\VoIP Video SIP SDK
     x64 SDK: C:\Users\Admin\AppData\Local\VoIP Video SIP SDK x64

How to collect log information on Android?

Use this method to set log level verbosity and toggle logging to file:
AbtoPhoneCfg.setLogLevel(logLevel, logToFile);

  • – logLevel must be in range 0..7 (0..5 on older SDK’s), 0 to disable logging and 1-7 to increase verbosity.
  • – logToFile is a boolean value to toggle output to file

Recommended way to enable verbose logging:
AbtoPhoneCfg.setLogLevel(7, true);
// or
// abtoPhone.initializeForeground(notification);

By default SDK output log information to Logcat.
To output information into file:

  • 1) set logToFile option to true
  • 2) check that AndroidManifest.xml includes permission:
  • 3) for Android 6-9 also need to ask for WRITE_EXTERNAL_STORAGE in runtime

Log files are located in [SD CARD]/Downloads/[App package name]/logs on Android 10 and above (does not require point 2 and 3), whereas on older versions of Android logs are located in [SD CARD]/[App package name]/logs folder

How to collect log information on iOS?

Logging on iOS is configured using logLevel property of AbtoPhoneCfg class:
@property(class, nonatomic, assign) int logLevel;

  • – logLevel must be in range 0..5, 0 to disable logging and 1-5 to increase verbosity.

Recommended way to enable logs
in Swift:
func application(_ application: UIApplication, didFinishLaunchingWithOptions
launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
   AbtoPhoneConfig.logLevel = 5

in Objective-C:
- (BOOL)application:(UIApplication *)application
didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
   AbtoPhoneConfig.logLevel = 5;

Note that when logs are enabled, i.e. logLevel > 0 then SDK also will generate log files in application sandbox path, which are located in AppData/Library/Caches. Developer can collect log files from device using Xcode: select Window menu option => Devices and Simulators => select device => find and select your app => press gear icon located at the end of the app list, select Download container and choose folder to store container in. When container is saved you can inspect xcappdata using Finder, just select file, open context menu and choose “Show Package Contents” then navigate as usually to AppData/Library/Caches and locate files log_[data].txt

I want a free softphone.

Our solution is a commercial Software Development Kit to quickly build a custom softphone solution for your company or distribute it to your customers under your brand.

I want to make free calls to mobile phones in other countries.

You should consider buying sip service from one of the providers. ABTO Software offers a solution to build sip client that can be used with such sip account.

I need a webphone.

Please contact us to receive webphone version details.

Can I distribute the customized softphone free of charge?

Yes, after purchasing our license you are free to distribute as many copies of your softphone on the basis of our SDK as you need with no additional payment.

Where should I start?

Go to folder C:\Program Files (x86)\ABTO Software\VoIP Video SIP SDK\binary
it contains SDK dlls and compiled example applications.

For example you can start our ‘MlSampleWindowCPP.exe’.

Also you can review or use as base for own app source code of our examples from folders:

c++ – C:\Program Files (x86)\ABTO Software\VoIP Video SIP SDK\MlSampleWindowCPP
C# – C:\Program Files (x86)\ABTO Software\VoIP Video SIP SDK\MlSampleWindowCS
Delphi – C:\Program Files (x86)\ABTO Software\VoIP Video SIP SDK\MlSampleWindowDelphi
VB – C:\Program Files (x86)\ABTO Software\VoIP Video SIP SDK\MlSampleWindowVB

I did not receive your download link.

Please contact us and we will provide you with all details.

My trial has expired.

Please contact our representative and will give you another trial license.

How to register VoIP SIP SDK on my machine?

SDK is registered when you setup it.
In case when you’ve received updated file – simply replace existing one, no need to register it again.
If app reports error ‘80040154 Class not registered’
register manually in following way:

a. Run cmd.exe with Administrator permissions
b. Type command: cd “C:\Program Files (x86)\ABTO Software\VoIP Video SIP SDK\binary\”
c. Type command: regsvr32 SIPVoipSDK.dll

How to register sipphone on target machine?

Is required to copy dll dependencies and register ‘SIPVoipSDK.dll’ on another PC using regsvr32 command.

a.  All files required for registration from “binary” folder:
b.  For successful work you also need:
codec_*.dll – codec files
Interop.SIPVoipSDK.dll – this file is required when your app is .net based
libspandsp.dll – this dll is required only with codec_g726.dll or codec_g722.dll

Can I make calls to other sip phones from your sip client?

Yes, absolutely. You can call to other sipphones using our application.

Which codecs are available for your softphone? Can I use other codecs?

Please check the codecs list on our Features list or open Settings of the softphone. Please contact us to consult about using other codecs.

I do not have audio devices on the machine. What should I do?

SDK automatically detects that case and starts properly.

If you would like to start SDK in silent mode (without access to audio devices) set option in source code:

or do same via config file:

a. Open ‘C:\Users\user\AppData\Local\VoIP Video SIP SDK\phoneCfg.ini’ in notepad
where ‘user’ – currently logged user name
b. Find line ‘LocalAudioEnabled=1’, replace with ‘LocalAudioEnabled=0’
c. Save changes, run app

I cannot register on SIP Server.

First of all, please check whether all registration credential and other settings are right are correct. Also please check firewall settings and try different network interface in the softphone settings.

Contact us for details.

Remote side can hear me, but I am not able to hear them.

Please try different network interface in the softphone settings.

The sound quality is not satisfying.

Please go to Settings of the softphone and try different Echo cancellation, Noise reduction, and Auto gain control settings.

I cannot use my mp3 file with your softphone.

Verify does ‘lame.exe’ was copied to same folder with ‘SIPVoipSDK.dll’.

SDK will automatically convert mp3 to wave and play it.

Does your SDK support audio stream?

If you would like to play audio buffer instead of wav file – yes, SDK supports this. Look at the method IAbtoPhone: PlayBuffer, and sample application MlSampleWindowCPP with example how to use it.

I want to make calls to countries with blocked VoIP.

a. Establish VPN connection. You need to setup one more system wide “Local area connection”. We recommend to solve this task using OpenVPN (look more )

b. Start and configure our sipphone with VPN settings. This task is not very difficult. You have just set SDK’s network interface setting equal to connection name, created on previous stage.
Contact us if you have problems with doing these tasks.

I want to send and receive faxes online.

Please contact us to try our T38 Modem solution.

I need something else.

Please send us a detailed description of your business need and we will help you with your project.