AT&U=4.0.9
It will upgrade and reboot. you should see:
Zimodem Firmware v4.0.9-sportster
sdk=v4.4.7-dirty chipid=3 cpu@240
tot=8192k heap=230k fsize=1404k
READY.
After that you should be able to type the following:
ATPT"0:23=COFFEEMUD.NET"
OK
ATPT"1:8080=CBBS.MITSALTAIR.COM"
OK
.