Singer Chris Brown is reportedly spending a lot of time with girlfriend Rihanna before leaving for singing tour.Brown, 23, also wants to stay in touch with Rihanna through telephone calls while he is away.''That's his girl and they're talking and trying to squeeze in as much time together as possible before he jets out of here," hollywoodlife.com quoted a source as saying."(Chris will) miss Rihanna. I know they will talk all day and text back and forth. Then, [he's] going to get back home and have a $5K cell bill. It's cool though. To him, Ri's worth a whole lot more, so he ain't tripping," the source added.Brown's tour is scheduled in several countries of Europe and South Africa and will start Nov 14.