I see what you're going through. I work on customer support in an ERP service company. I really like it, and I think I am doing a good job. However, I am often getting pulled by the arm to go into the sales team, I've managed to say no so far, but it's an endless struggle.
If you like what you're doing then you're OK. I have some colleagues that like selling, some don't. Both are needed either way to keep the business going.