None, this isn't even an ISP level setting, it's a telco setting. The ISP can request that it be turned on and if your line quality signal is good enough, they can.
You can't, log into the modem you're using and review the line stats there. I have VDSL, on mine it shows: D (interleaver depth): 1 on VDSL it means that while it is on interleaved, a depth of 1 is functionally equivalent to fast-path.
Ssh into the modem and run the following command: /etc/init.d/dsl_control status
which should give you a bit of information, including about the interleaving.
Also run mtr -ezb4w -c 100 22.214.171.124 or similar to get an idea about the RTT to the next hop (which is typically not your DSLAM) combined interleaving delay for up- and downstream needs to be smaller than the RTT to the next upstream hop.
Thanks guys! Unfortunately, I can't find interleave depth value anywhere, only Latency [Interleave delay] : 8ms/3ms
Now since delay > 0 does that necessarily imply that I'm on the interleaved channel? Anyway to get that depth value?
When I enter this line, it returns this "-ash: mtr: not found". May you please give further explanation on this?