TCP port 69 is used for TFTP (Trivial File Transfer Protocol).  AltiGen IP phones use this protocol to download firmware updates from a TFTP server.  AltiGen provides a lightweight TFTP server program called "tftpNAT".  Note that despite it's name and design intent, many NAT firewalls do pose problems with TFTP.

Many 3rd party IP phones also use TFTP to retrieve their firmware and configuration. 

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