Customers in Portland and Seatle will be the first to try out a joint marketing effort between Verizon and Comcast.  

The companies announced Monday that Comcast will sell wireless bundles for cable customers looking to buy a new smartphone or add a new phone and data plan. The companies said they expect to roll out the deal to other cities later.

The initial Comcast promotion will provide a prepaid Visa card, up to $300 in value, for customers who sign up for the Verizon-Comcast bundled service. A press release said there are some restrictions: to qualify a customer must be signing up for a new Xfinity Double Play or Triple Play package.

And the customer must be a new Verizon Wireless customer purchasing a qualifying smartphone or tablet data plan; or an existing Verizon Wireless customer adding a new line of service or upgrading their service with a new smartphone or tablet, both with a new two-year customer agreement.

Customers will receive the prepaid Visa cards by mail.

Details are here:  www.comcast.com/wireless.