Verizon Wireless' approval of new standard-rate mobile coupon programs after a slowdown of that process felt by marketers is evidence of a major internal debate at wireless carriers.

The question is, at what point will opening the carrier pipes to marketing directed at subscribers endanger that relationship with a flood of commercial messages that could potentially overwhelm the network?

While carrier executives hesitate to go on record, they certainly voice their frustration in one-on-one conversations about the challenges that mobile marketing, content and commerce poses.

The key challenge is obviously the fallout of a bad experience that a consumer -- in other words, the carrier's subscriber -- has with a mobile retailer or content provider or even an advertiser.

Very often, it is the carrier that bears the brunt of the consumer's frustrations -- an angry call to the carrier's customer service center or, worse, a cancelled or failed renewal.

Perhaps what mobile marketers are not getting across clearly, or at least not reassuring some of the leading players such as Verizon Wireless, is that mobile marketing, content and commerce are revenue drivers that should not be ignored.

To that argument, the carriers' comeback is staple: What percentage revenue does mobile advertising, marketing or commerce contribute to the network's bottom line? Fair point. As things stand today, not much.

But it is the future where the potential lies. Say what the carriers may, the horse is out the barn door.

Consumers are increasingly expecting to conduct some of the same activities they do online on their mobile devices: communicate through written word via email, search, shop, play games, listen to music, view videos, find directions and check business documents. Add to that the mobile phone's original features of talk and text.

So carriers can't wish these data services away. Providing them through better devices and affordable data plans is no longer a point of differentiation -- it is an expectation.

However, the economics still don't bear out for carriers.

A major worry is the strain such services will place on the network. What if mobile video really takes off? How will the network cope with the increased number of page requests for such rich media downloads? What will that do to basic services such as talk and text -- the bread-and-butter of carriers and still the biggest yardstick by which they are judged?

Mobile commerce -- what if a transaction goes sour? Does the subscriber take out her frustration on the carrier and call the customer service number if the connection dropped just as the checkout process was underway?

So what should carriers expect when mobile commerce does take root in a big way -- which it will when smartphone penetration doubles or trebles from the current estimated 20 percent mark?

Let's talk about mobile advertising. What if those ads become really ubiquitous and all units are not just simple 6x1s but full-screen pop-ups? What if the units are animated and voice-enabled, thus forcing a quick fumble to turn down the volume? What does that do for the content consumption experience?

These are but a few of the issues likely debated within carriers' upper echelons. Bottom line for them, they don't want to jeopardize revenue from biyearly contracts worth anywhere from $1,200 to $2,500 per subscriber. How do they itemize mobile marketing, content and commerce revenue on a per-customer basis?

Indeed, mobile marketers must sit down with senior carrier executives and discuss these issues. It should not take pressure from a publication such as this -- the Verizon Wireless issue over mobile coupons (see story) and the planned SMS fee increase last fall (see story) -- to convince a carrier to make a decision that makes sense for overall business and recognizes market trends.

At the same time, it speaks volumes of the lack of communication that marketers cannot engage with carriers on serious issues without fear of retribution. After all, mobile marketing cannot succeed without the full participation of the carriers. But carriers must first think of themselves as mobile marketers, too.