Sales has been working day and night putting together a response to a complex RFP for a major contract with an important customer. Now, hours before the deadline, it's finished. With a satisfied look the VP of sales attaches the file to an e-mail cover letter, checks the recipient's e-mail address twice and pushes "send."

The system seems to slow to a crawl as the big file is uploaded, but after what seems to be an hour the screen displays the legend "Your e-mail is sent." But just as he relaxes an error message hits his mailbox. The recipient's e-mail system has refused to accept the message. The reason: the file exceeds the e-mail system's size limit. It's too late to print it all and send it via overnight messenger.

A frantic hour later, after a call to the corporate help desk that pulls a senior IT technician off other urgent work to deal with the emergency, they send the document using file transfer protocol (FTP).

This was a situation that carrier-level voice over IP ( percent) system supplier Sonus Networks -- whose equipment carries 40% of all carrier-level percent traffic worldwide -- experienced frequently enough that FTP became a routine solution for its users. They are constantly exchanging software releases, manuals, bid responses, logs from switches experiencing problems and other large files with their customers, who are the largest voice/data carriers in the world.

However, said Ian Schneiderman, computing services manager at Sonus Networks, FTP has several disadvantages that sent them looking for a better solution. "FTP is a complex technology to use and to manage. Setting up a customer is a lengthy process that we didn't want to be doing constantly. Then FTP has limitations with respect to security and control once a file is sent."