US mobile operators routinely refuse to support certain short codes for services they see as competing with their own, according to BusinessWeek. In some cases the competition is clear, such as when Alltel, (NYSE: AT) T-Mobile and Verizon (NYSE: VZ) Wireless denied the short-code application of Rebtel, a VoIP provider that offers cheap international calls. A Verizon spokesman says, “we don’t need to provide special access to our customers and network to a company that’s in direct competition with us.”

In other cases, though, the definition of competing is a little more cloudy. BW says that four banks, including two of the nation’s 20 biggest, had their short codes denied by AT&T. They weren’t offering anything telecom-related, they just wanted to offer their customers mobile banking services. AT&T (NYSE: T) eventually relented and approved the applications, at about the same time it launched its own mobile banking services in partnership with a couple of other banks. AT&T also stalled on approving PayPal’s short code, only giving it the go-ahead in May, when most other operators approved it shortly after PayPal announced its mobile services in early 2006.

While the operators’ rejection of the short codes may be objectionable, it’s unlikely that it’s illegal, since there are no clear-cut laws or rules being violated. However, Public Knowledge and some other advocacy groups have filed a petition with the FCC, asking it to clarify that text short codes are subject to the same non-discrimination rules as voice phone numbers. The groups cite Rebtel’s experience, as well as Verizon’s highly publicized refusal to approve a short code for the abortion-rights group NARAL Pro-Choice America (though Verizon later reversed that decision).