https://www.dslchecker.bt.com/sdsl/sdslchecker.welcome SDSL does use the audio frequencies, but isn't faster downstream and does cost a bomb.

If line bonding, do the used lines retain separate phone numbers?

No idea. All I know is plenty of people on these forums use it to get faster downloads.

In reply to a post by camieabz:

If line bonding, do the used lines retain separate phone numbers?

yes, because the voice services are distinct and only the broadband is bonding. There may be one IP address or more, depending what type of bonding is in use.

bonding does not affect the telephone numbers assigned to the line

In reply to a post by camieabz:

If line bonding, do the used lines retain separate phone numbers?

As others have said broadband has no connection with telephony beyond a shared cable. So yes, you'll have two separate phone numbers. If you go that route you should bear that in mind when reporting a fault

We used to have a dual bonded line solution at work. It did a good job overall turning two poor 54db lines into a single 5Mb/1.2Mb connection. The only thing I would say is that sometimes if one of the lines was having a bad day it destabilised the entire connection. That wasn't always the case though and might have been down to our Cisco router. Another factor is that you might find you need a box that you have no idea how to configure.

Overall I'd say our office connection was a good decision but it's a lot better now that we have a fibre-based leased line

Did you measure the Attenuation after the bonding, to allow comparison with the 54 db?

Or in lieu, the speeds before bonding?

Distance?

The 54db was determined in the early days before the Cisco box was attached using a domestic modem/router - we didn't know enough about the Cisco box to know what it thought

Performance-wise one line was running at about 3.5Mb/s, the other was worse at around 2Mb/s. Distance-wise it's just under 5km. The route is entirely underground but the last half is rural.

Interesting in that it looks almost a simple aggregation of the two lines, as opposed to some more complex arithmetic, eg a Root 2 (1.414) improvement above the simple aggregation, ie around 7 Mbps.

On the other hand, 5 Mbps looks of the right order for 5 km.

In reply to a post by eckiedoo:

Did you measure the Attenuation after the bonding, to allow comparison with the 54 db?

bonding at the TCP/IP level doesn't affect attenuation or at the DSL level.