You can definitely work on specific sales skills and improve them, but it concerns me when you say you're "not a people person".
To do well in sales, you have to understand and like people - this is the one common thread that all successful salespeople share. You don't have to be a smooth-talking, "life of the party" type to do well in sales, but you DO have to show genuine interest in your customers and be concerned about their needs. You can fake it for a while, but they'll see through it soon enough.
Being an ISR (Inside sales rep) amplifies this significantly, as the tone of your voice reveals a lot more than you think.
Anyway, explain more about the job. Are you prospecting/cold calling, or is their an established client base already? Is it a complex product that requires after-sale follow-up? What is the commission structure like?