Linux Upgrading

I am using RHL 7.1
I want to upgrade to RHL 8/9.
But the problem is that my modem driver are not supported by their kernels (GM56 SM PCI Internal Modem).
Is their any way that I upgrade without upgrading the kernel or when i boot into Linux I geta option to choose the kernel to boot from haing co-existence of different kernels.
It will help me so that during my Internet work, I can use the kernel of RHL 7.1

Thanks for your help.