Line transfer to 21CN

I received an email from IDNet today. It reminds me that the UK telephone network is being upgraded by BT to the new "21st Century Network" and that my exchange was upgraded (last March). I have not upgraded to the faster "up-to-24mbps" service. I enjoy speeds of 7-6.5 mbps most of the time and my connection is stable. The BT calculator suggests I would not get more than 7-8 mbps if I upgraded so I see little point in buying a new router and risking stability. I

The email from DNet tells me that my line is due to be transferred to 21CN on Friday 26th March:

�no change is required to your modem/router and no change will be made to the service settings. The work is carried-out by BT at your Exchange. Whilst your line is being switched to the new equipment there will be a short period of downtime - this will happen anytime between 6am and 8pm on the date specified.�

A couple of queries:

1. How long is the downtime?
2. More seriously, does the transfer to 21CN cause any longer-term stability issues?

Edited by ARD (Wed 17-Mar-10 15:47:15)

Hi ARD

The downtime is usually no more than 10 minutes, just as long as it takes the engineer to move the cabling from one piece of kit in the exchange to another.

The DSL modulation is still for ADSL Max so there should be no change to the broadband characterisics.

Regards
SImon

Many thanks, Simon, for your clear answer.