I was installing Cisco IP Phones 7945 and 6945 using CUCME 9.0 in a 2921 router. The problem is that the 6945 phones don´t register in CUCME; i have tried with SCCP and SIP with the same results. The firmware that the phones are using is 9-2-1-0. The IOS of the router is 15-2-4 universal. The 7945 phones register with no problems; the problem is only with the 6945 phones.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...