The replication strategy for this company would be to implement a Mirrored Configuration between the three sites making one of the sites the controlling site. The controlling site (Site A) should be one of the sites with Internet access which has the dial up connection facility. The controlling site should synchronise data with the other Internet enabled site (Site B) using E-mail Replication and should synchronise data with the remaining site (Site C) using the Asynchronous method over the dial up connection.
The controlling Site A should connect to Site C at, say, 8:00pm and then should issue an e-mail replication to Site B at 8:30pm. Site B should be set to check for Internet mail at 9:00pm. By 9:30pm, both Site B and Site C will have been updated with the Site A's changes for that day and Site C will have prepared it's changes for Site A and Site B will have sent back, via Internet mail, it's changes for Site A. Site A may then check for Internet mail at 10:00pm, knowing that it should receive Site B's changes for that day. Site A will then connect to Site C at 10:30pm and receive its changes and will update Site C with Site B's changes which it has just received. Site A will now be updated with the changes from Site B and Site C. Site C will also have been updated with Site B's changes. However, Site B will not yet have been updated with Site C's changes and so Site A should issue another e-mail replication to Site B for 11:00pm. Site B should schedule a check for Internet mail at 11:30pm.
Given that all connections are dial-up connections, then all 3 sites may be updated with each others changes with 7 phone calls over a period of 3½ hours.