Local call option is available only in certain areas.
However if you have performed calls via Local call method previously and you no longer see the option to change to Local call method again please firstly check phone number that is displayed under: "Account" tab > "This mobile number" section. Make sure that phone number is set in correct format, including country code and phone number. Having correct format is correct as application needs to recognize the area that you are located in order to show Local call method.
If you are using iPhone device there is an option to hide and show local call option.
Navigate to "Account" tab in the app > Scroll down to "Voice calls" and open the section, disable "Callback" option and local call will appear back if it's available in your area.