MTNL Delhi SNR very low, phone is dead but internet is still working

[Jagat]

2 days ago, I had downstream SNR 35 dB and line attenuation 18dB. Now phone is dead (no dial tone) and downstream SNR is 8dB, line attenuation is 28dB. But there seems to be no effect on the internet, I am getting same download speeds as before.

-- dead tinypic image removed --

I had heard that if SNR drops down close to 6dB then ADSL cannot work properly. But this does not seem to apply to MTNL Delhi

 

[amish]

Phone line has two wires. If one wire breaks phone call can not complete a loop. But DSL signals can still pass over working wire.

(This explanation was given to me by lineman when I had exact same issue)

 

[Jagat]

Okay, the lineman came and told me exactly as you have explained DSL works even when one of the wire is broken. He fixed the cable and now it is back to normal.