I use Lakes Region Septic. They are located in Brookfield.
Tel. # 603-522-6246
http://lakesregionseptic.com/index.html
It would be good to locate the covers of your tank and have them exposed when the pumper arrives. If they have to locate and dig them up, it will probably cost you more. There should be a drawing/sketch of your septic system layout that was used when the house was built. If you don't have it, the Town might have a copy of it.
If you are getting a smell, it might be that your leach field is plugged up and not draining well.