Have them dial your NextPBX number. NextPBX will automatically detect that a fax is coming in and set itself to receive the fax; it will then show up in your Messages under the phone number that the fax was sent to.
Have them dial your NextPBX number. NextPBX will automatically detect that a fax is coming in and set itself to receive the fax; it will then show up in your Messages under the phone number that the fax was sent to.