Have Cellular Service Companies Colluded?

I have always wondered whether something funny is going on between large cellular companies. I find it odd that each major cellular carrier offers one, and only one, great feature: AT&T offers Rollover Minutes that don't expire, Verizon offers a huge network with unlimited "IN" calls, T-Mobile provides an abundance of anytime minutes for relatively low rates, Sprint-Nextel offers Direct Connect, Alltel provides unlimited communications with My Circle and My Cirlce message packs. Is there pact not to tread too far into the competition's territory?

Things have changed some. Verizon tried to compete with Sprint-Nextel by offering Push-to-Talk, a feature aimed at businesses that offers instant communication. Verizon's version doesn't seem to have the same pizazz as Nextel's...but at least they tried. T-Mobile's myFaves has been heavily advertised, especially during the NBA season. This has myFaves and the Fav 5 has done so well that the Saturday Night Live crew decided to make fun of families dealing with Fav 5 issues. Time will tell just how well Verizon and T-Mobile will do by opening things with these offerings.

Why doesn't anyone try to dominate and offer an additional cant lose feature? T-Mobile's myFaves is as close to the jugular as it gets. Being more aggressive could result in a feature war where everyone loses profit margin, which no major company is interested in.

Note 1 - Metro PCS is certainly an exception, although I'm not sure how well known they are on a national scene.

Note 2 - To be clear, I have NO PROOF of, nor am I accusing anyone of, collusion or any other wrongful behavior.