New here and doubt: pin call (sip? dial-in?)

Hello to all! I’m an active user of different instances, eagerly anxious to learn about to create my own. But before that, I just discover in 8x8 the pin call option with a number to Argentina (I’m from Argentina). I do have students that have very bad difficulties of connectivity and this can be an amazing alternative. But, as connectivity issue they also have some economic issues so…would be nice to know if it’s any instance of no charge call of Argentina or how can I do that.

Thanks in advance

any comment about it? It’s for a good cause