After configuring Microsip with your account details navigate to the small downward pointing arrow and open the Settings panel.
In the Settings panel make sure that Single Call Mode is unticked
To transfer a call, first make or receive a call.
Now click the transfer button and you will see two options.
A Blind Transfer will send the call over to the person you have dialled instantly.
An attended transfer will allow you to first call the person you have dialled and speak with them yourself before transferring the call to them.
Both selections will open up a new panel to input the number you would like to transfer the call to.
When doing an Attended Transfer a new call is established with the person who you want to transfer the call to, after you have spoken to them click transfer again.
Then select the number to transfer the call to.
This will transfer the call to them and end the call for you.