[cisco-voip] ISDN SIMULATOR ISDN BRI-U and BRI-S/T

[Manoj Kalpage]

Hi All,
I am looking for ISDN simulator for CCIE voice lab. I found there are
two type of ISDN simulators at http://www.vconsole.com/ as bellow.

ISDN BRI/ST
http://www.vconsole.com/2-Port-T1/E1/PRI-+-8-port-BRI-S/T-ISDN-Simulator-p-15.html

ISDN BRI-U
http://www.vconsole.com/2-Port-T1/E1/PRI-+-8-port-BRI-U-ISDN-Simulator-p-14.html

First thing, I cannot understand is what is the different between
BRI-U and BRI-S/T and next thing is which one is good for CCIE voice
LAB.

Are these good or anyone know any other product which is better than this?

Best regards,
PERE