AT&T’s recent quarterly earnings were solid, but it’s clear that the mobile provider is shaken by recent competitive moves from T-Mobile.

AT&T last year was forced to adopt service plan offerings similar to T-Mobile’s “JUMP!” program. More recently AT&T tried to get out ahead of T-Mobile’s plan to pay early termination fees for mobile customers who switch to T-Mobile, though AT&T’s offering is smaller and limited to only T-Mobile customers. In response, T-Mobile is treating AT&T’s offer as a ticket to a free try-before-you-buy period with T-Mobile’s network.

These pressures haven’t affected AT&T’s bottom line yet, but subscriber numbers are growing at an ever-slowing rate in the increasingly saturated U.S. mobile market. AT&T is now searching for new revenue opportunities, including abandoning any pretense of net neutrality by charging content providers for data customers may have already paid for. Also, to get more revenue from the customers it currently has, AT&T is now encouraging them to add more devices to their existing service plans.

AT&T today announced that customers will receive $100 in bill credit for each new device they add to an AT&T plan. The offering includes smartphones, tablets, feature phones, mobile hotspots, and wireless home phones added by either new or existing AT&T customers. The offer is currently available both online and in AT&T stores, though the company is describing it as a “limited tome offer.”

Obviously, the cost of most mobile devices would eclipse the initial $100 rebate. Add to that the fact that mobile providers charge monthly for data for each device on a plan, rather than for a shared pool of data, and the offer begins to make real sense for AT&T. Still, for customers who are already looking to add a tablet to their AT&T mobile plan the extra $100 off their next bill could make their decision an easier one.

Image via AT&T