The 34-year-old is one of four catchers still in Cubs camp, joining Welington Castillo, who will be the regular backstop, George Kottaras and John Baker. Whiteside and Baker were non-roster invitees.
Whiteside saw that Rangers are in need of a catcher, as former Cub Geovany Soto was injured and will be sidelined 10-12 weeks. That creates an opening.
"[The news] is obviously out there," Whiteside said. "If you watch ballgames and that kind of stuff, [the news is] running across the bottom line [of the television]. It's out there and it's noticeable. You just try to come in, get your work in, and do what you can to prove yourself to this team and any other team that's out there looking."
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.