Yes, PPP callback with E1-R2 is supported.
controller E1 0
framing NO-CRC4
clock source line primary
cas-group 1 timeslots 1-15,17-31 type r2-digital r2-compelled ani
cas-custom 1
!
interface Group-Async1
ip unnumbered Ethernet0
encapsulation ppp
async mode interactive
peer default ip address pool ABCD
ppp callback accept
ppp authentication chap pap
group-range 1 10
Thanks, Mak