asterisk users - Jun 2005 - CallerID Bug?

hi, all:

I have two phones, one is SIP/200, another is IAX2/203. Now, i use 
IAX2/203 call to SIP/200, sometime CallerID display is 203(at phone 
SIP/200), sometime display is 200. Is this a bug? Please help me!

Sorry my english.

Li Yuqian