The turnaround cycles get shorter and it looks like the sales department run out of (patience|answers|clues|excuses). I got a reply from the technical department:
Case ID: 1392853 Dear Mr Wissel Thank you for the reply. I will address your concerns on the transfer loss due to overheads (such as cable condition, distance from exchanges, etc), as you are familiar with all the factors that affect a broadband connection's downloading speed. You may wish to know that our Broadband 3500Kbps plans can only be used on ADSLs activated line for 3500Kbps. If the existing line served by exchange MUX has a dB loss of more than 30, it is not within specification. Under such case the line will be converted to local MUX. I seek your understanding that although we own the cables, condition of line wiring within users' premises may vary. When you sign up for our 3500kbps plan, we will need to ensure that the line condition is within the required specification. Thus, I regret once again that we are not able to guarantee that you will receive the maximum download speed.
Getting close... So I asked back:
thank you for your reply. I realize being persistent enough finally gets me the answers I'm looking for.
To rephrase my question: I want to know if the LINE can support 3500Kbps. I didn't ask if I can achieve maximum download speed all the time.
So the current conclusion is:
a) The signal loss between ADSL modem and MUX must be lower that 30db to be able to support 3500Kbsp. And ideally a measurement would be performed on a hot day since copper cables have higher losses with higher temperatures.
b) Cable length and quality is a big issue. If cabling in my block the MDF room looks like the one above it might not work at all.
What do I need to do to get a measurement and assessment of the line quality? Since there is a specification, there must be a measurement to verify it.
I seek your kind understanding, that I want a verification BEFORE I sign up as a customer. You have sufficient fine print in your contracts, so I would end up paying the subscription even if the line doesn't match the specifications.