Sales office in USA
I presume your question has to do with the various options for registering your business in the US. I see two options that would suit your needs:
1. Registering a Foreign Entity of your Indian company in the US: your company will be officially registered in a state of your choice and will need to file taxes like any US entity.
The disadvantage of this approach is the fact that your company would need to produce an equivalent of a Certificate of Good Standing in India, then have it Apostilled before submitting the registration for Foreign Entity to the US state of your choice. It might take time and would cost extra.
2. Forming a new domestic LLC: you can form an LLC in the US and list your Indian company as the owner of that LLC. This is faster, cheaper, and you will own a domestic US company, which could make it easier for you to do business in the US in general. Of the two options I described I would recommend you to opt for this one.
If you have any specific state where you want to open an office I would recommend considering that state as the state for your business registration. If you don't plan to establish your sales operations in any particular state I would recommend you to consider Wyoming or Delaware as the state of registration.