Here are some examples of how to use chan_misdn in the dialplan (extensions.conf):
[globals] OUT_PORT=1 ; The physical Port of the Card OUT_GROUP=ExternE1 ; The Group of Ports defined in misdn.conf [misdnIn] exten => _X.,1,Dial(mISDN/${OUT_PORT}/${EXTEN}) exten => _0X.,1,Dial(mISDN/g:${OUT_GROUP}/${EXTEN:1}) exten => _1X.,1,Dial(mISDN/g:${OUT_GROUP}/${EXTEN:1}/:dHello) exten => _1X.,1,Dial(mISDN/g:${OUT_GROUP}/${EXTEN:1}/:dHello Test:n)
On the last line, you will notice the last argument (Hello); this is sent as Display Message to the Phone.