No dial-tone but DSL still working?

Quick question for those who are familiar with DSL and telecoms: we’re having a winter storm at the moment with high winds knocking lots of limbs and branches off trees. Walking the dogs this morning, I noticed a handful of branches on the phone lines and a couple of largish limbs which looked like they may have hit the phone lines as they fell. The phone lines themselves are still up. We currently do not have a dial-tone on any of the phone hand-sets yet our DSL is still working normally, with no appreciable latency or impact on bandwidth. How can the DSL still be working if we’re not getting a dial-tone on our phone line?

Equipment failure at the telecom facility. Your line is still physically sound all the way to the local phone company switching station if your DSL works.

Your DSL/Phone goes to a Digital Subscriber Line Multiplexer (DSLAM) where the digital and the phone get split. Typically this happens at the Central Office, but sometimes they can install remote DSLAMS. (Sometimes they call these Central Offices, but they are really remote DSLAMS) So, between you and the DSLAM everything is fine, but between the DSLAM and the voice circuit, your line is dead.


It could be a bad DSL splitter at the central office, the POTS (plain old telephone service) port itself, and it actually can be the physical loop. It is rare but I have seen loops where I have dsl sync but no dial tone. Usually it’s the other way around though. Only seen this 3 times in 2 years of being a telecom field service tech though. In those three cases, one was caused by a light short top to ring, another by a light ground tip to ground, and the last the tip side was completely open and somehow the dsl was still working on ony one wire of the pair (NO idea how, but it was very close to the CO). A problem at the central office is signifigantly more likely, particularly if your service is through an ILEC, because most CLEC’s will have all residential equipment prewired - so no one is messing with it. ILEC offices are generally adding and removing cross connects all day so it’s more likely that something will have been messed up by mistake.

Thanks for the feedback, guys, it’s very much appreciated. I have a service ticket in with our phone service provider now.