Those entering on visitor visas will generally be granted six months admission (the maximum allowable is one year) on entry. It may be possible to obtain a six-month extension to the visitor visa as long as the candidate will be maintaining visitor status, and there are good reasons to do so. It is sometimes possible to change status to another longer-term visa whilst in the US as a visitor, as long as the candidate advised the relevant US Embassy or Consulate of this possibility beforehand, or there was no pre-conceived intent to do so.
This category of visa should be applied at the US embassy in Bangkok/Chiang Mai. Applications made in other countries often run a high risk of being turned down. The most common reason for refusal of B-1/B-2 visas is the applicant showing insufficient evidence of social, family or economic ties to their country of residence that would ensure that they would return there following the visit to the USA.
The B-1 visa is intended only for business activities that are a “necessary incident” to your business abroad. This covers a wide range of activities such as attending meetings, consulting with associates, engaging in negotiations, taking orders for goods produced and located outside the United States, attending conferences, and researching options for opening a business in the United States (such as locating or entering into a lease for office space). Generally speaking, you cannot engage in any activity or perform a service that would constitute local employment for hire within the United States. What constitutes local employment for hire will depend on the circumstances of each case, but generally speaking, any activity you perform in the United States must be directly connected with and part of your work abroad.
If you are coming to secure funding for a new business, you cannot remain in the United States after securing the funding to start actual operations or to manage the business, unless you change status to another classification that authorises employment in the United States.
You must be able to show you have sufficient funds to cover the expenses of the trip and your stay in the United States. You must also show you maintain your residence abroad, which you have no intention of abandoning, and that you have other binding ties which will ensure your return abroad at the end of the visit