I am trying to retrieve faxes received, but the documentation is not very clear as to where I can get the extensionId or the accountId? does anyone know where this information is? also, what is the best endpoint to run?

I am trying to retrieve Faxes received, however, I am not sure where the accounted and extensionId are? The documentation is not very clear as to where to get this information from. Does anyone have a guess? also what endpoint do I need to run with this?