I have a certificate that's a relic from my days on NWA. The certificate is good for 12,000 miles total off of 2 domestic tix. It expires on 12/31/10. The code with the certificate indicates I can only book by phone. I'd like to start off '11 with no Delta Skypesos and welcome the opportunity to blow through my remaining miles on a domestic transcon. I've found some itineraries that fit my situation well and would be 38,000 with the discount (2 RT at 50,000 normally) my questions are:

-How easy is it to book these flights? I've established through the computer that there are multiple flights worth 25,000 RT, if I get on the phone are they suddenly going to claim these flights are worth 32,500?

-Will I incur charges for booking by phone? I don't think I should since I can't book online but my gut says they'll probably charge me anyway.

Sorry if these questions sound noobish but I'm not very familiar with Delta as my only association with them was via NWA.