TE121B

The TE121B is a single span, selectable T1 (24-channel), E1 (32-channel), or J1 (24-channel) card.
The following configuration is to configure the card with 30 usable channels.
File:te121b.jpg

/etc/dahdi/system.conf

loadzone=au
defaultzone=au

span=1,1,0,ccs,hdb3,crc4
bchan=1-15,17-31
dchan=16

If you have an echo cancelation card installed like I do you also need to include the following line.

echocanceller=mg2,1-15,17-31

/etc/asterisk/chan_dahdi.conf

signalling=pri_cpe

group=1
channel=>1-15,17-31