After about 6 hours of non productive Google searches we pose the following question for assistance. Thanks in advance. We use MacBooks Pros running Yosemite and have recently decided we need to do file transfers (probably only pdf and def NOT fax protocol) between two machines USING DIAL UP POTS lines. This is a security concern and broadband connection approach is NOT an option. We did this all the time (20 yrs ago) but we are struggling to do it now! Here's what we have figured out we know (OR DON'T KNOW) so far: 1. We can use the USRobotics 5637 USB modem with Yosemite 2. Not sure what application we can use to dial up and connect and transfer the files (used to use ProComm or other Terminal program). Any thoughts or suggestions on how to do these file transfers? Thanks!