Last update 10 December 2011
On old BT Wholesale based connections the IP Profile is what determines your maximum download speed. It is set by your connection speed (also know as sync or sync speed) according to the table below.
If you get a lower sync than previously the profile normally falls within 75 minutes. If you get a sync higher than previously it takes from a few hours up to 5 days to rise to match.
Small increases take longer, the reason being that your line could be flapping around a threshold and BT don’t want their systems having to update the settings for your line frequently. Large increases should be quicker as the system realises you probably had a one-off slow sync.
I find overnight is usually a minimum and 3-4 days normal.
(Note that before August 2008 there was a 3-day fixed update time, with “blip-logic” to make it almost instantaneous in certain circumstances. At the time of writing, many documents elsewhere including I believe some BT help ones still describe that system rather than the new one).
The only way to get the current value of your IP Profile is to run the BT Speed Test. Some ISPs show it on your Control Panel, but the value there can be incorrect. (See also the Entanet and Plusnet paragraph below).
Profiles can get “stuck”, the automatic system failing to update it as it should. The most common time this happens is on first connection to BT ADSL from no broadband or LLU broadband and the most common stuck profile is 2000kbps. You need to contact your ISP to get it freed.
A common problem on Entanet reseller and Plusnet connections is that they hold a copy of the BT IP Profile in their own system (at their Radius Servers). This should update automatically within a short time of the BT setting changing, but the update system seems to fail quite frequently. If this happens contact your ISP support.