I had run into this 448kbps number elsewhere. What do you mean by "raw"? is *this* the maximum uplink allowed by the modems?
The 448K is the max upstream connection (sync) speed that BT has defined for its A(asymmetric)DSL Max product throughout the UK. Similarly it has defined 832K for its ADSL Max Premium product. There is nothing you can do to change these, nor do they offer any other products at your exchange (but see below). They are both subsets of the (ANSI/ITU) Standard ADSL (G.DMT) which offers an upstream sync speed of up to 1.3 Meg.
Sync speeds, both up & down, are the raw speeds the bits are carried between your exchange and your modem. These include both the actual data that arrives at your PC, usually counted in Bytes, and all the protocol overheads needed to carry them, like an envelope. Usually the actual data throughput speed is about 83% of sync speed. Hence your upstream speedtest of 300K+.
The modem plays no part in limiting these speeds other than adhering to the Standards and negotiating for a stable connection.
I believe at one time BT offered a Symmetric DSL of 0.5, 1 or 2 Megs, but not sure they still do.
Please post your router stats (see here: How to get your router line stats
for your router) so we can see if you are getting what you should.
I doubt BT would shut you down whatever you were doing as long as it was lawful.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 19 Meg WBC
Edited by XRaySpeX (Sat 27-Oct-12 01:25:41)