DTW Controller voiced concern regarding both the lack of communications jacks available for mandatory relief briefings and air carrier operations involving two companies that operate for the same airline.

Narrative

We are required to do overlap briefings after giving up positions. We are almost always training; that takes up the 2 primary jacks. Overlap is to be done in the emergency jack. Both our 2 main Local frequencies bleed over on each other making actual monitoring of the frequency; let alone the position impossible. We also have a Ground Control frequency with no emergency jack at all. There is a physical jack but the wrong frequency. FAA management is well aware of this as it has been an issue since we started doing overlaps. If I'm responsible to do the monitor time; shouldn't the FAA be responsible to provide me the necessary equipment? Second item; we have two air carriers that fly for multiple carriers. Both fly for one airline; one also flies for two other airlines. We have 2 terminals separated by a runway. Perhaps this new runway crossing phraseology will help; but this is a ridiculously unsafe situation! The agency has been aware of this for years. How long before someone issues taxi instructions and the aircraft turns right instead of left; crossing a runway? Sometimes; most times; its dark out and you can't actually see the aircraft. Sometimes the aircraft are simply painted white. I have to believe this is an issue in a RADAR environment as well. Recommendation: A. Fix our frequencies B. Assign different call signs to air carriers when flying different carriers.