Returns a single rolled-up total of voice service usage for a time window, rather than the per-bucket or per-row breakdown of the other reports. Requires Reseller or Super User scope. from and to are required Unix timestamps. Narrow the result with the optional domain, service_type, vendor, and reseller filters, where domain of * means no domain filter. Omitting from or to returns 400. This is the domain-scoped form: the report is confined to {domain} through the access-control object, so an Office Manager or higher within that domain may call it.