Look at the manual, by copying and pasting this URL into a browser. Or go to BT.com and navigate through to the user manual section:
http://bt.custhelp.com/cgi-bin/bt.cfg/php/enduser/cci/bt_adp.php?p_sid=tQw3J-Yj&cat_lvl1=1243&cat_lvl2=1899&cat_lvl3=1918&p_cv=3.1918&p_cats=1243,1899,1918&p_faqid=11453
binky mcfuddle, April 2010