Datacenters are noisy places. On occasion it is necessary for an administrator or technician to troubleshoot a problem in the datacenter while on a phone call or conference call. Unfortunately, these can be long, drawn out conversations, depending on the issue at hand. Mobile phones are pretty lousy in these circumstances: the person in the datacenter can't easily hear over the noise, and the mic tends to make things unpleasant for the listeners.
In-ear monitors make it easier for the person in the datacenter to hear, but don't do a whole lot for the people listening on the other end.
What features should I be looking for in a headset for making phone calls in the noise of the datacenter less noticeable for all involved?