The RBK13 package consists of one RBR10 router and two RBS10 satellites, thus you already have a "router".
What you need for a new service provider depends on what kind of service they provide.
Typical "cable ISP's", such as Spectrum, Comcast, Cox, will provide service via a coax cable which needs to be connected to a "cable modem". Fiber providers typically provide a converter box that may or may not include a modem.
As you already own a "router", I suggest calling the new provider and asking them.
