[Asterisk-Users] Setting a "Forward" to an external number on your phone

[Jui]

Hi!

Maybe I have just been looking on the wrong pages but there is a 
question that is very important for me. I already studied some 
Demo-Dialplans and made some basic experiences with Asterisk. But what I 
need to find out is how I can handle this.

I am leaving my office and I want to tell asterisk to forward calls now 
to my mobile phone by just hitting a key (on my IP-Phone) or by using a 
special key-sequence.

How can this be handled because I need to change the dialplan based on 
some information coming from a device attached to a channel.
When back in my office I hit the key again and the calls are now routed 
to my IP-Phone (or ISDN-Phone on zap-channel) again.

With IP-Phones I can imagine just unregistering the phone and having a 
dialplan with a fallback-option or something like that. But what if I 
want to tell asterisk to forward calls from now on to a number I want to 
manually add just for today (hitting a key, entering the new target 
number and that's it). where can I find some information on how to make 
this feature available.

Jui