Cisco 857, Cisco 877 or Cisco 1801 ADSL router on a BT line

(note: your ISP doesn't have to be BT)

I was experiencing this issue with a Cisco 877, running IOS 12.4(4) T1, Advanced IP Services feature set. The router was barely staying in sync for more than 15 minutes at most.

So i contacted the folks at Insight (that I'd bought it from), and was given the following (quoted from Cisco):

After escalating the interoperability issue of C857, C877 and C1801 routers with British Telecom lines, a new firmware has been made available which will fix the problem you've experienced. Attached is the firmware and a description on how to use it. This firmware is the same for 857,876,877,1801,1802,ADSL HWIC. As described in the doc, filename must be adsl_alc_20190.bin so just remove the _2542 part before downloading to flash.

This document has some background, as well as some instructions. Basically, you need to

• copy this on to your router
• rename it to adsl_alc_20190.bin
• then reload your router.

Ta da, it all works.

Hope this helps someone.

Update: it seems there have been some more updates to the firmware. Download if you want.