[SOLVED] How can i flash hook for incoming call on fxo chn?

Hi,
How can i flash hook for incoming call on fxo channel?
What are the settings? How can i use this feature on softphone for example zoiper?
I tried *2 and ## but asterisk opens a new fxo channel.
Thanks,

I solved this with dynamic features.

Use this http://forums.digium.com/viewtopic.php?f=1&t=80554&sid=2164b9927c836c85ac5f3e58f236d908 configuration.