Depending on your router / IOS use one of following commands.
show dsl int atm 0
show controllers vdsl 0
e.g.
#show controllers vdsl 0 | in Attainable|Speed
Attainable Rate: 53188 kbits/s 9678 kbits/s
Speed (kbps): 0 39999 0 9652
#show controllers vdsl 0/0/0 | in Attainable|Speed
Attainable Rate: 21728 kbits/s 1116 kbits/s
Speed (kbps): 0 20475 0 1115