I want to add new module in Asterisk

I have started to write a new module and put it in asterisk/res folder.

In this module I want it can call functions in chan_sip.c (I have created my functions in chan_sip.c).

But when running, the program show the error of function symbol.

So what I have to change the makefile or something to make it work?

Try speaking to the developers. lists.digium.com and irc.freenode.net #asterisk-dev

Thanks! I sent it to asterisk-dev mailing list. But if someone can help me that is great!!!