3410 does have a security keyboard lock!

- It's at [Menu] 4-6-2 and then your security code is asked when you unlock
with [Menu] *
- Also the 3410 can lock the keyboard on a timer (unlike 3315). You can
use this with a security or without.

3410 is a superb phone if you don't want a toy, just one that makes calls
and has some useful functions at a budget price.
I even think it has the
edge over the 3510i orange thingy as the 3410 being
DCT3 works well with LM for changing screensavers and pictures etc. Even
the clock screensavers are better; more detailed.
If you want a budget phone, spend £10 more over the 3310 on 'pay and go',
plus all bonus stuff is enabled in 3410 already.
I enjoyed that!
/Smug Mode.
Mole.