Everyone is different, so you need to go with what will reach the most customers (obviously cant please everyone). most people phone my mobile first, others phone landline (if they have more free minutes to landline rather than mobile etc). some will phone mobile, but check there is a landline number advertised! some people like an 0800 number (generally older people who dont have mobiles - since its a free call to them),
i usually avoid anyone with an 08 number unless they also advertise or give me a 01/02 (look in electric fix catalogue - has their 01 number advertised as 'mobile friendly' in the first few pages)
for yellow pages, many people start at beginning of section working their way though - even with a company starting with 'C', its still a few pages in. other will skip to section and start reading from first page they get to (i.e if they look and see electricians start page 732, they might open and skip to 740, and start from there rather than back to 732).
Getting all contact details etc set to the majority of people is hard!