Load ringtimer from database

I am trying to enable users to enter their own ring time from the telephone. I've found out that "ringtimer" value is written in asterisk database and MySQL database. However, I also found out that changing these values has no effect, because the ringtimer is still hardcoded in extensions_additional.conf. That doesn't appear to make sense.

Would it be possible for you to modify extensions_additional.conf, so that the ringtimer value is read from asterisk database? So instead of:

{noformat}
exten => 36,1,Set(__RINGTIMER=xx){noformat}

Something like:

{noformat}
exten => 36,1,Set(RT=${DB(AMPUSER/36/ringtimer)})
exten => 36,n,GotoIf($["${RT}" = 0]?defaultring)
exten => 36,n,Set(__RINGTIMER=${RT})
exten => 36,n(defaultring),...{noformat}

It would also make sense to put this in a macro, or even better, dialparties.agi.

I am sorry if this seems trivial, but it is rather important to me.