I Am pretty sure it will come handy for all that we still using ISDN as back up Meth. this are the L1 through 3 tshoot from cisco.
Plus a loop back ISDN test call enjoy it
Layer 1 troubleshooting
http://www.cisco.com/warp/public/129/bri-layer1.html
Layer 2
http://www.cisco.com/warp/public/129/bri-layer2.html
Troubleshooting ISDN BRI Layer 3
http://www.cisco.com/warp/public/471/isdn_q931_ts.html
ISDN BRI S/T
http://www.cisco.com/en/US/customer/prod/collateral/routers/ps274/product_data_sheet09186a0080091b87_ps259_Products_Data_Sheet.html
Lo test Call
http://www.cisco.com/en/US/tech/tk801/tk379/technologies_tech_note09186a0080094b21.shtml
Plus a loop back ISDN test call enjoy it
Layer 1 troubleshooting
http://www.cisco.com/warp/public/129/bri-layer1.html
Layer 2
http://www.cisco.com/warp/public/129/bri-layer2.html
Troubleshooting ISDN BRI Layer 3
http://www.cisco.com/warp/public/471/isdn_q931_ts.html
ISDN BRI S/T
http://www.cisco.com/en/US/customer/prod/collateral/routers/ps274/product_data_sheet09186a0080091b87_ps259_Products_Data_Sheet.html
Lo test Call
http://www.cisco.com/en/US/tech/tk801/tk379/technologies_tech_note09186a0080094b21.shtml