Gauge willingness to compromise control
Currently, telcos such as Verizon or Sprint exert influence in what content can operate on their networks, as well as the associated costs. Even major brands find themselves struggling to access certain networks, and the result is large chunks of an audience can't be reached. For example, the NFL's mobile content is available exclusively through Sprint. While this is a risk, it is not a show stopper; a little research before committing to the project will provide enough insight to make a go/no go decision.
Other times, a manager must adapt the voice of the brand to work on mobile networks. Recently, NARAL, a political organization, was denied the right to broadcast certain text messages to its constituent audience because Verizon policy would not allow it. While this was reversed, and most brands are not as controversial, it is still crucial to ensure that the carriers will allow messages to be promoted through their networks.
The mobile space is not like the web -- the concept of net neutrality does not exist here. Instead, carriers can, and will, exert influence over the content that is provided to consumers. Brand managers must be aware of this, and have plans on how to deal with the potential impact.