Hubgets is a collaboration solution that is very much connected with Presence. If the tool "sees" that you are offline, it will automatically prompt the calling party to leave a voicemail, which will be sent to you in a notification via email.
However, if you would like to have calls transfered to a colleague in your absence, this can be done by enforcing a call routing rule in the backend of Hubgets, by the Admin/Owner of the organization.
When you are online in Hubgets, you can transfer the call to any team member without answering the call. Please see the image below to check out how to do it.