Please check in skype developer doc.
They provides Mobile SDK and APIs for skype call.
Please refer Microsoft doc for Starting a call from an Android mobile device For Business.
Button skypeButton = (Button) findViewById(R.id.button);
final EditText SIPAddress = (EditText) findViewById(R.id.SIPAddress) ;
final CheckBox videoCall = (CheckBox) findViewById(R.id.videoCheck);
skypeButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String uriString = "ms-sfb://call?id="+SIPAddress.getText().toString();
if (videoCall.isChecked()){
uriString +="&video=true";
}
Uri uri = Uri.parse(uriString);
Intent callIntent = new Intent(Intent.ACTION_VIEW, uri);
startActivity(callIntent);
}
} );
And for Skype SDK for Android as per doc you can call using that.
try {
SkypeApi skypeApi = new SkypeApi(getApplicationContext());
skypeApi.startConversation(skypeName.toString(),
Modality.AudioCall);
} catch (SkypeSdkException e) {
// Exception handling logic here
}
You can also use URI to call for these refer this link Skype URI tutorial: Android apps and answer How to start a Skype call from an Android app?