What happens if NaOH is substituted for NH3?

In a lab experiment, we had to add NH3 to certain solutions. We had three separate solutions of Br-, I-, and Cl-, all combined with AgNo3. After precipitation, we had to add NH3 to each and then centrifuge the test tubes to separate the precipitate from the supernatant. What would happen if NaOH is substituted for NH3? Are we allowed to substitute NaOH for NH3?