Hello! To send a fax at USPS, you need to visit your local post office, confirm they offer fax services, prepare your documents, and pay the fee. A friend suggested Municorn's FAX From app for iPhone, and it has been excellent. The app is incredibly easy to use, lets you fax from anywhere, and is very convenient. I’m very pleased with this alternative. For a detailed comparison, check here
https://comfax.com/usps-fax/