An OFTP Session

The following example demonstrates a very simple OFTP session, using arrows to indicate the direction of the command flow.

• Company A makes a call out to Company B.
• Company B responds with an SSRM stating that they are ready to start using the OFTP protocol.
• The companies then swap SSID commands. (This is the equivalent of telling each other their identity).
• Company A then sends an SFID stating that they have a file to send.
• Company B responds with an SFPA stating that they are willing to accept that file.
• Company A proceeds to send the data.
• After 4 data blocks, Company B sends back a CDT. (This is the equivalent of making a small response to indicate you are still on the line).
• At the end of the file, Company A sends an EFID to state that this is the end of the file.
• Company B then sends back an EFPA stating that the file was successfully received.
• Company A has no more files to send, so now gives Company B the opportunity to send their files, by sending a CD (Change Direction command).
• The process then starts again (there is no need to sign on again with the SSRM and SSIDs), and Company A receives a file from Company B.
• At the end of the file, they change direction again with a CD command.
• Company A acknowledges the file by sending an EERP.
• Company B acknowledges the receipt of the EERP by sending the RTR.
• Company A has nothing more to say so passes control to Company B.
• Company B also has nothing to say and so sends an ESID, on receipt of which Company A hangs up the line.