I use CPT code 99288 when the physician is on the phone with the EMS service and providing guidance on the way to the hospital (i.e. cardiac arrest). There are no documented NCCI edits when coding your critical care (99291 with the 99288).
The only way I would use this code, however is the physician documents in his ED note that he spent time on the phone directing the EMS service. Otherwise, you have no documentation of the services.
Remember, if billing for Medicare patient, you would use G0390 if the "critical care trauma team" responds and is activated.
Hope this helps