Still, there's no guarantee on getting visas.
I read (many postings here on the hubb) it could take a few days to a few weeks to get a Sudanese visa depending on the mood of the issuer. Lonely Planet said this would be a crapshoot. And keep in mind holy day, which means government offices closed Friday and Saturday, and hopefully there's not a religious/secular holiday happening...
In Addis, I first hit the Egyptian consulate. A notice on the wall indicated visas were usually issued in one day. For me, it took 5 working days (and one weekend..#*@&!) - a whole week! After that, I went to the Sudanese consulate fearing the worst, and got my transit visa in 24 hours! My experience; everyone else's varies.
Chiang Mai, Thailand