[asterisk-users] caller id problem

[unplug]

Hi,
  Does anyone can tell me how to set the caller id shown in the callee
phone?  When I use hard IP phone to make a PSTN call, the number
displayed in PSTN phone correctly using set(callerid(num)).  However,
the caller id won't be displayed when I use software IP phone to PSTN.
 Does any method/function to control the caller display in all case
(including call forwarding)?
Thanks