Laserjet 3030 Voice/fax answering problems on Shared telephone line

Hi, having quite a problem here with a HP Laserjet 3030 printer/scanner/copier/fax. The printer scanner works fine with the computer no problem, however i am experiencing problems with recieving faxes or voice calls. The fax is attached to a single line, along with a telephone & it uses a BT callminder answerphone. Unfortunately this answerphone does not pick up until about 8-10 rings, the maximum i can set the fax to is 6 rings. This means that the fax is answering the voice calls, at 6 rings. At the same time though, the fax will not recognise an incoming fax & answer automatically, but waits for the 6th ring & then recieves the fax. Is there someway to make it answer faxes automatically in the first few rings, but not pick up at all if it detects that it is not an incoming fax but a voice call instead, so that the voice calls can ring through to the answermachine. Setting the fax to manual operation is not an option, neither is a dedicated line, so ideally i need the fax to be able to work without interfering with the ordinary telephone calls.
This is on a UK BT ADSL landline, with all filters correctly installed.