It really depends on the carrier, but I would not recommend it. Are they doing the billing inhouse and considering outsourcing? If that's the case maybe they would be willing to let you start with one line of their business. For example, you submit allof the HealthPartners claims and they continue the others until they are sure they want to transfer all.
Personally I do not like when a provider wants to do this. I know they want to take it slow, test out the waters, but that really doesn't work for the billing service. It's a lot of work to get an account running. If you are new and starting out obviously you've got more to consider. You need to get started and experience is the best way.