B410P on Trixbox 2.3.0.4

Hi all,

I am desperately trying to get our Digium B410P working on Trixbox 2.3.0.4. I have tried just about everything that I can think of (being a linux n00b), and I have followed all the possible steps laid out by some very helpful users on these forums. However, I keep hitting a wall when trying to "make B410P".

Here is what I am seeing...

[trixbox1.local zaptel-1.4.4]# make b410p
grep: /lib/modules/2.6.18-8.1.14.el5/build/include/linux/autoconf.h: No such file or directory
[ -f mISDN-1_1_3.tar.gz ] || /usr/bin/wget ftp://ftp.digium.com/pub/zaptel/b410p/mISDN-1_1_3.tar.gz
tar -zxf mISDN-1_1_3.tar.gz
make -C mISDN-1_1_3 install
make[1]: Entering directory `/usr/src/zaptel-1.4.4/mISDN-1_1_3'
echo 1_1_3 > VERSION ; \

cp /usr/src/zaptel-1.4.4/mISDN-1_1_3/drivers/isdn/hardware/mISDN/Makefile.v2.6 /usr/src/zaptel-1.4.4/mISDN-1_1_3/drivers/isdn/hardware/mISDN/Makefile
export MINCLUDES=/usr/src/zaptel-1.4.4/mISDN-1_1_3/include ; export MISDNVERSION=1_1_3; make -C /lib/modules/2.6.18-8.1.14.el5/build SUBDIRS=/usr/src/zaptel-1.4.4/mISDN-1_1_3/drivers/isdn/hardware/mISDN modules CONFIG_MISDN_DRV=m CONFIG_MISDN_DSP=m CONFIG_MISDN_HFCMULTI=m CONFIG_MISDN_HFCPCI=m CONFIG_MISDN_HFCUSB=m CONFIG_MISDN_XHFC=m CONFIG_MISDN_HFCMINI=m CONFIG_MISDN_W6692=m CONFIG_MISDN_SPEEDFAX=m CONFIG_MISDN_AVM_FRITZ=m CONFIG_MISDN_NETJET=m
make: Entering an unknown directory
make: *** /lib/modules/2.6.18-8.1.14.el5/build: No such file or directory. Stop.
make: Leaving an unknown directory
make[1]: *** [all] Error 2
make[1]: Leaving directory `/usr/src/zaptel-1.4.4/mISDN-1_1_3'
make: *** [b410p] Error 2

As far as I can tell, I am missing the "build" module (is this supposed to be part of the kernel)? I have tried downloading what I think is the correct RPM for this version, but it just tells me "already installed".

ANY advice would be very much appreciated.