The places I've seen this at had specific verification codes for this. One had a simple static code per person that the hands-on guys looked up in a physical binder on their desk. Very disaster proof.
The other ones had a system on the internal network in which they looked you up, called back on your company phone and asked for a passphrase the system showed them. Probably more secure but requires those systems to be working.
The other ones had a system on the internal network in which they looked you up, called back on your company phone and asked for a passphrase the system showed them. Probably more secure but requires those systems to be working.