Hi, and thank you for your interest!
Zoiper Android 2 is being translated using Weblate, a web tool designed to ease translating for both developers and translators.
Translation project for Zoiper Android 2 into Spanish currently contains 1062 strings for translation and is 32.1% complete.
If you would like to contribute to translation of Zoiper Android 2, you need to register on this server.
Once you have activated your account just proceed to the translation section.