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Cisco 876 and T-DSL - no sync


I experience a strange phenomenon with a CISCO876-SEC/K9. The router is properly configured and works well with a (very old German) T-DSL access port (only 768kbps ADSL).

Now I connected the router to a "brand new" T-DSL subscriber line, a T-DSL 3000.

The router doesn't sync. The CD LED is blinking, and the DSL remains down. The technician tested the line with a dsl tester, and he said everything is OK with that line, it must be the router.

Now I am a bit lost - the router runs IOS 12.4.15T11(MD).

Should I downgrade to an earlier IOS, to make the router compatible to the German Telekom DSLAM(s)?

Should I apply the ADSL modem patch "Asymmetric Digital Subscriber Line (ADSL) Firmware", release 4.0.18?

But the descr. says that this patch is only meant for BT subscriber lines. So I don't really expect a change in behaviour.

Is there any one out there who has experiences with CISCO876 against current T-DSL 3000 lines and brand new Telekom DSLAMs?

Thanks a lot!

Best regards,

Olaf Jacobi

Cisco Employee

Hi Olaf,

I hope you are fine, I have worked in the past with some DSL cases, in which the DSL modem was not able to sync with some  british or german DSLAMS. I was wondering if you have tried to hardcode the dsl operating mode from the ATM interface. (sometimes when you leave it as auto, the chipset is not able to sync with the DSLAM)

interface ATM0
dsl operating-mode auto

If that does not fix the issue. I strongly suggest you change the firmware from the chipset, sometimes you need to upgrade, sometimes to downgrade, I know it sounds hard I made these things on the past and they can be a pain.  I dont believe that changing the IOS on the router could fix it. Please let me know.

I may check for any compatibility issue.


Itzcoatl Espinosa