[Serusers] Date header in INVITEs

Has anyone already implemented a Date: header for INVITEs in an easy and fast method? I'm looking for a quick plug-in that will send the date in GMT format that looks like this (in strftime format):

Date: %a, %d %b %Y %T GMT

where %a is day of week (three letter), %d is the day of the month (01-31), %b is abbreviated month name (three digit), %Y is the year as a decimal number including century, and %T is the time in 24 hour notation (HH:MM:SS)

I have some SIP UA devices which set the timestamp of outgoing calls on caller ID (analog phones.) SNTP is not an option, so using a Date: header is the next best thing. Maybe someone who has already incorporated this into SER might have something handy and save some time on my end...

JT