I get the following error when attempting to compile mpg123 for music on hold in asterisk.  Note also this post:
http://lists.digium.com/pipermail/asterisk-users/2005-September/125845.html
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# cd /usr/src/
[root@linux40 src]# ls
AMP  asterisk  asterisk-addons  debug  libpri  linux-2.6.9  redhat  zaptel
[root@linux40 src]# cd asterisk
[root@linux40 asterisk]# make mpg123
build_tools/make_version_h > include/asterisk/version.h.tmp
if cmp -s include/asterisk/version.h.tmp include/asterisk/version.h ; then echo; else \
        mv include/asterisk/version.h.tmp include/asterisk/version.h ; \
fi

rm -f include/asterisk/version.h.tmp
[ -f mpg123-0.59r.tar.gz ] || wget http://www.mpg123.de/mpg123/mpg123-0.59r.tar.gz
--11:49:51--  http://www.mpg123.de/mpg123/mpg123-0.59r.tar.gz
           => `mpg123-0.59r.tar.gz'
Resolving www.mpg123.de... 192.67.198.7
Connecting to www.mpg123.de[192.67.198.7]:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 159,028 [application/x-tar]

100%[========================================================================================>] 159,028      158.23K/s             

11:49:52 (157.78 KB/s) - `mpg123-0.59r.tar.gz' saved [159,028/159,028]

[ -d mpg123-0.59r ] || tar xfz mpg123-0.59r.tar.gz
make -C mpg123-0.59r linux
make[1]: Entering directory `/usr/src/asterisk/mpg123-0.59r'
make CC=gcc LDFLAGS= \
        OBJECTS='decode_i386.o dct64_i386.o decode_i586.o \
                audio_oss.o term.o' \
        CFLAGS='-DI386_ASSEM -DPENTIUM_OPT -DREAL_IS_FLOAT -DLINUX \
                -DREAD_MMAP -DOSS -DTERM_CONTROL\
                -Wall -O2 -m486 \
                -fomit-frame-pointer -funroll-all-loops \
                -finline-functions -ffast-math' \
        mpg123-make
make[2]: Entering directory `/usr/src/asterisk/mpg123-0.59r'
make[3]: Entering directory `/usr/src/asterisk/mpg123-0.59r'
gcc -DI386_ASSEM -DPENTIUM_OPT -DREAL_IS_FLOAT -DLINUX          -DREAD_MMAP -DOSS -DTERM_CONTROL                -Wall -O2 -m486 -fomit-frame-pointer -funroll-all-loops                 -finline-functions -ffast-math   -c -o mpg123.o mpg123.c
mpg123.c: In function `shuffle_files':
mpg123.c:225: warning: implicit declaration of function `time'
mpg123.c: At top level:
mpg123.c:480: warning: initialization makes integer from pointer without a cast
gcc -DI386_ASSEM -DPENTIUM_OPT -DREAL_IS_FLOAT -DLINUX          -DREAD_MMAP -DOSS -DTERM_CONTROL                -Wall -O2 -m486 -fomit-frame-pointer -funroll-all-loops                 -finline-functions -ffast-math   -c -o common.o common.c
gcc -DI386_ASSEM -DPENTIUM_OPT -DREAL_IS_FLOAT -DLINUX          -DREAD_MMAP -DOSS -DTERM_CONTROL                -Wall -O2 -m486 -fomit-frame-pointer -funroll-all-loops                 -finline-functions -ffast-math   -c -o decode_i386.o decode_i386.c
gcc -DI386_ASSEM -DPENTIUM_OPT -DREAL_IS_FLOAT -DLINUX          -DREAD_MMAP -DOSS -DTERM_CONTROL                -Wall -O2 -m486 -fomit-frame-pointer -funroll-all-loops                 -finline-functions -ffast-math   -c -o dct64_i386.o dct64_i386.c
as   -o decode_i586.o decode_i586.s
decode_i586.s: Assembler messages:
decode_i586.s:44: Error: suffix or operands invalid for `push'
decode_i586.s:45: Error: suffix or operands invalid for `push'
decode_i586.s:46: Error: suffix or operands invalid for `push'
decode_i586.s:47: Error: suffix or operands invalid for `push'
decode_i586.s:67: Error: suffix or operands invalid for `push'
decode_i586.s:70: Error: suffix or operands invalid for `push'
decode_i586.s:81: Error: suffix or operands invalid for `push'
decode_i586.s:83: Error: suffix or operands invalid for `push'
decode_i586.s:86: Error: suffix or operands invalid for `push'
decode_i586.s:161: Error: suffix or operands invalid for `pop'
decode_i586.s:211: Error: suffix or operands invalid for `pop'
decode_i586.s:296: Error: suffix or operands invalid for `pop'
decode_i586.s:315: Error: suffix or operands invalid for `pop'
decode_i586.s:316: Error: suffix or operands invalid for `pop'
decode_i586.s:317: Error: suffix or operands invalid for `pop'
decode_i586.s:318: Error: suffix or operands invalid for `pop'
make[3]: *** [decode_i586.o] Error 1
make[3]: Leaving directory `/usr/src/asterisk/mpg123-0.59r'
make[2]: *** [mpg123-make] Error 2
make[2]: Leaving directory `/usr/src/asterisk/mpg123-0.59r'
make[1]: *** [linux] Error 2
make[1]: Leaving directory `/usr/src/asterisk/mpg123-0.59r'
make: *** [mpg123] Error 2
[root@linux40 asterisk]# uname -a
Linux linux40 2.6.9-1.667smp #1 SMP Tue Nov 2 15:09:11 EST 2004 x86_64 x86_64 x86_64 GNU/Linux
[root@linux40 asterisk]#