How does this dialer work?
The dialer will look for things that match the T9 query as well as search your contacts that have the string of numbers associated with their phone number. 

For example if you have contact John Smith with phone number 123-456-7890 and you dialed "78" he would show up because that string matches part of his phone number. If you dialed dialed "56" he would also show up because that matches his name "Jo" as well as part of his phone number "56".

I hope that helps!