All PMS use the UTC timestamp except for INFOR* and SUITE8 which will return the hotel's timezone.
Unfortunately, it is not possible to get the timezone from the property management system. As an example, if a hotel is integrated with MEWS, the timestamp shown in our API will be in UTC. The timezone would then need to be converted by the recipient of the API request.
*Please note that unfortunately we only support the Infor integration for hotels that have an existing connection between Impala and Infor. At this time we are no longer able to accept any new request to integrate with hotels using Infor PMS.