Keypad lock and sending DTMF during call

[Guest Miniman99]

Just got a C500, which is great however I've got a minor issue.

When you have the keypad locked and you recieve AND answer a call, you cannot press any of the number keys (for DTMF) during that call without first unlocking it.

I ask this because a number of systems I use, are capable of outcalling to me and I need to enter an authorisation code or similar, so once I've answered the call, I want the whole keypad to unlock.

Anyone know how to do this?

I have tried search, but it didn't bring up any results.