AT&Ts failed bid for T-Mobile will be quite expensive [telecom]

As a T-Mobile subscriber (from back in the Omnipoint days!) and a former shareholder, I've been following this particular part of the story with a great deal of interest.

Unspoken by most reporters (maybe all...) is that TM _had_ roaming agreements in many of these areas with the various (formerly) small and local, third party, carriers.

When AT&T gobbled them up, the roaming agreements were often _not_ renewed [a]. Hence in many areas, TM customers suddenly woke up one morning and found they no longer had workable service.

I have friends in California (hi, Steve) and in Michigan who, if not for TM's "hotspot at home" WIFI based alternative, would be carrying around useless bricks.

Hopefully AT&T will now allow TM voice callers back on their network.

It's my understanding that in order for roaming to occur there has to be a roaming agreement in place. Whether roaming is allowed or not is determined by whether the original customer's company has authorized roaming to occur i.e. T-Mobile has to allow roaming on another operator since if their customer roams on another system they have to pay out money to roam on the foreign operator's system. Generally you won't be able to roam in any area where the customer's company has a wireless presence (no matter how good or bad the quality of that connection is.) If the operator does not service the area there's a better chance that a roaming agreement will be in place.