Then you'll need to call your local Comcast office. You may have to look it up in the phone book. I looked on my bill and they have the local office address and hours of operation, but not the phone number.
Then try calling 1-800-COMCAST. It is only a guess for me since I have the full CDV package (and all calls to Canada and the US are included), but you will probably pay $0.05 per minute for any call outside your area code.
The OP has the "Local with More" calling plan. See the FAQ here.
* 5 cents/minute for in-state and out of state long distance
It is $15 cheaper than the regular CDV plan, which is worth it if you make less than 5 hours of long distance calls a month. And voicemail is an additional $4 per month with this plan. If you need voicemail, then the breakeven point is about 3.7 hours of long distance calls per month
The only problem is the OP is having difficulty finding out what is "in-state and out of state long distance."