HCJes

Wow... a three digit access code is not that secure. Anyone could just try three digits and get through.

Does the access code get enter before the LD number or are you prompted for it after dialing. If before, try changing the dialing prefix.

If after: you could setup one of the speed dial buttons on the fax so they can press one button after they send the fax to send the digits.

tataylor

I also use three digit LD codes. I have approximately 100 in use at all times. Basically 1 in 10 chance of finding a valid one. Users are kept in line by telling them that I track every key stroke made on every phone so if they are attempting to find another valid LD code I will know.
It sounds like LD company is providing the codes, if this is the case the the code is entered post pbx.
I went away from this and now actually use my pbx auth codes. This way I control all aspects of the codes and do not have to deal with my LD carrier at all. I needed BARS to implement this. With BARS and auth codes you can set it up so that say for fax machines you would not need to enter a LD code.

pbxn

I use something similar with Bell. You should be able to request that the code restriction be removed from that number. Contact your Sprint LD group.
Don't like the 3 digits, I use 6 here.