How do I fax a doc. for signature, rather than email?

I am using Adobe Acrobat to fill a form, required be the state as a Plan of Care. I can't mail it, due to Dr.'s office policy, I have to fax it. I could do that with PDFfiller, and I can fax but not fill online with RingCentral. I was hoping Adobe Acrobat and EchoSign would allow me to do both. Any ideas?