If the law is similar in Nevada to the law here in Manitoba, the answer is a simple, "It depends"...
Persons Serving (either the person suing, or a person hired to do so) legal papers (Summons, etc) may not enter Private Property (in this case, the Workplace) without permission. Where I work, Process Servers have been escorted off the property any number of times, because they have tried to ambush someone in the Parking Lot. THey have been told that once the Employee is off the property, they can attempt to serve them there, but the only way they can legally Serve an Employee is if they agree to allow a Supervisor or Manger to bring the Employee to Human Resources, where they can then legally Serve the person.
(If you're going to hire someone to Serve the Summons, make sure that you read-up on what is legal for them to do, and what isn't, because if they do not do it legally, the person is not legally required to show-up, and any judgement against them for failure to appear will be automatically overturned.)
Among some of the things the Courts of Queen's Bench requires Process Servers to follow here are: They must present ID if/when requested. They must allow the Documents to be examined to determine authenticity (and this does NOT mean the documents have been Served). They must Serve the documents according to the dictates of the Human Resources Department. Why? Because improper Service negates the Summons.
Good Luck!