Timestamps in Sinch APIs are used for expressing a moment in time. They're represented using the ISO-8601 standard. Examples of timestamps are the fields send_at and expire_at in the Send a batch message operation.
A time offset can be specified in accordance with ISO-8601 time offsets from UTC. If no time offset is specified (local time in ISO-8601) then UTC will be used.
All timestamps returned by the API will be represented in UTC time, with millisecond precision.