There are some important things you need to consider when you choose a second number app:
You can find hundreds of apps on the play store, however you need to check if it allows you to make calls to the location of your choice.
If you use an iPhone, get a free second phone number app for iPhone from all the available options.
There are different types of payment options to choose from including pay per phone, pay per use, pay per phone number etc. Choose the best app which suits your requirements.
Opt for a free trial before making a payment. Most second number apps have a free trial period of 7 or 15 days so you can check the service before you buy.
Look for authentic customer reviews and ratings on their website.