I have a trouble with any Cisco 1721 ( I have tried with three cisco 1721) that I connect to two lines. I have installed a WIC 1SHDSL and a WIC 1ADSL. The SHDSL is a 2 Mb symmetric dedicated line, the ADSL is a 2048/320 standar, ULL, ETH.
I have tested the equipments with other lines and I do not have any problem. I have ruled out electrical problems.
The error that we can see after the restart is: "System returned to ROM by address error at PC 0x8000EC38, address 0x8000EC38".
The router can work 5 consecutive days and it can restart every 30 minutes during 2 consecutive days.
"sh ver" shows:
ios y mÃ¡s: Cisco IOS Software, C1700 Software (C1700-ADVSECURITYK9-M), Version 12.4(21a), RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2008 by Cisco Systems, Inc.
Compiled Mon 29-Sep-08 13:38 by prod_rel_team
ROM: System Bootstrap, Version 12.2(7r)XM2, RELEASE SOFTWARE (fc1)
I will try with 1800 series.
Let me know if you need more information,