how to change the default encoding format from pcm into alaw

i have installed the asterisk version 1.4. In that machine i installed the diguim card and connected to E1 PRI. I made the call to that PRI and the asterisk pickedup , to record the voice i issued the Monitor command through Asterisk manager interface. The voice recorded with .wav extension and it is in PCM encoded format. I want this to be recorded in ALAW codec. I tried to get this by editing the zaptel.conf as follows,
span=1,1,0,ccs,hdb3,crc4
# termtype: te
bchan=1-15,17-31
dchan=16
alaw=1-15,17-31

loadzone = us
defaultzone = us

in the above, i included alaw parameter newly, but then also the same result.

kindly give me suggestions or directions to achieve this?

Thanks in advance,
jankrishnan.

Hi The format is specified in the Monitor command.

Ian