I am looking to replace my sprint number with a number on my tmobile prepaid phone. However, I still want to KEEP my current sprint number and port that number over to my google voice. Is this possible?

I have a Sprint legacy SERO account and not sure if this is possible without messing up my account. In other words, I think the process might work like this:
Tmobile Number --> Replaces Sprint Number
Old Sprint Number --> Ported to Google Voice

I appreciate all the help