The problem has been isolated to the remote data terminal equipment.

Local System
 .----------.                                               
 |          |                                                Remote Data
 |          |                                                Terminal 
 |          |    Local Modem                Remote Modem     Equipment
 |          |    .-----------.              .-----------.    .----------.
 |          +----+           +------//------+           +----+          |
 |          |    '-----------'              '-----------'    |          |
 |          |                                                '----------'
 |          |                                                ^          ^
 |          |                                                |          |
 |          |                                                |          |
 '----------'                                             The problem is here.