Zinder is a transport hub, though distances are vast. SNTN buses connect to Niamey (about 14 hours). Buses to Agadez take around 8 hours but do not follow timetables — bush taxis are faster and leave when full, best tried in the morning.
Bush taxis also run south to the Nigerian border and sometimes all the way to Kano. For Chad, take a bush taxi east to N'Guigmi.