www.ukphoneinfo.com is a great site for finding area codes - and it works backwards too, so you can put in a number like 01234567890, and it will tell you it's in Bedford, but probably not valid.
08663 & 08665 aren't found, so either the call didn't come from the UK (in which case, surely it should come up as International?), or whoever was calling you inserted a fake CLI - in which case it was probably an international call centre...