Hi Robert,
You can find more information about using Survey123 with high-accuracy receivers here Use a high-accuracy receiver—Survey123 for ArcGIS | Documentation, including which receivers are currently supported.
Are you using iOS or Android devices for your field workers? The reason this is important is that there are some receivers that are currently only supported on certain platforms due to the vendors firmware.
I see you mention Trimble in your post, what model Trimble devices do you have? Currently on Android, the following devices are support: Trimble R1, R2, R8s, and R10. You can find more information in the above link in the Survey123 documentation.
As for iOS, with the latest released version 3.7 of Survey123, Trimble is not supported on iOS. However, in the upcoming 3.9 release to be available in April 2020, we will have added support for the Trimble R1. Note this requires a firmware update to your Trimble device to the latest version which was just released by Trimble. In coming months we also hope to add support for the Trimble R2 and other devices, made possible as Trimble updates and provides support via their firmware for those receivers for iOS. We currently have the 3.9 iOS and Android builds available in the Early Adopter Community, if you would like to test out support with your devices and receivers using the latest builds.
Regards,
Phil.