http://www.arrl.org/foreign-licenses-operating-in-u-s
Foreign Licenses Operating in U.S.
Foreign amateurs who wish to operate in the US and are not US licensees or citizens may do so in one of three ways:
Check the list of countries which have signed a reciprocal operating agreement with the US. If your country of citizenship and amateur license is not named in the list above, see if it is possible to obtain a CEPT license or an IARP from your home country. If none these are possible, then no reciprocal operating authority is in effect between the US and that country and operation is not possible in the US.
Foreign amateurs may, however, obtain a US license by taking and passing the appropriate license. Find information on obtaining a US license here. A US mailing address is required for application purposes. If a US license of any class is held by the foreign amateur, it supercedes any other operating authority when operating in the US. In that case, the US license MUST be used in place of any other operating authority. If the country holds no reciprocal operating agreement with the US and does not participate in CEPT or IARP, a US license is the only option.
US Call Sign Region Map
International Travel Host Exchange (ITHE)
http://www.arrl.org/obtaining-permission
How does a foreign amateur obtain permission to operate in the US?
There are three possibilities:
Operation under a multilateral reciprocal operating agreement with the US,CEPT or IARP
Operation under a bilateral reciprocal operating agreement with the US
Operation after obtaining a US amateur license. If a US license is held, it supersedes any other type of operating authority when in the US.
The FCC allows amateurs who are citizens of their home country to operate in the US provided that there is a reciprocal operating agreement between the US and the foreign country. The foreign amateur must carry two items when operating in the US:
1) Proof of an amateur license issued by the country of citizenship;
2) Proof of citizenship in that same country.
The foreign amateur must maintain his or her citizenship in their home country and the individual must also hold an amateur license from that country. There is no time limit on how long a foreign amateur can operate in the US as long as the foreign amateur maintains home country citizenship and an amateur license from that same country. Operation under CEPT is limited to short visits of approximately three weeks. An IARP is valid for the term authorized by the issuing authority. The FCC no longer issues reciprocal operating permits to foreign amateurs in lieu of the above.
Foreign Amateurs who wish to operate in the US may do so if the country of which they are a citizen and amateur licensee has entered into a bilateral or multilateral reciprocal operating agreement with the US. Such agreements can include areciprocal licensing agreement, CEPT license, or IARP. No additional permit is required — simply bring your original amateur license, issued by your home country when you visit the US; and be sure to identify your station while operating by the US call district identifier (e.g., followed by your non-US call sign.W3/G1ABC). You can find a map of the US call districts here and a listing of the states on the FCC Web page.
If your country of citizenship and amateur license is not named in the list of countries that have such agreements with the US, then no operating agreement is in effect between the US and that country–and operation is not possible in the US based on your home license.
Operation in the US by any person is possible if you seek a US amateur license. Any person, other than a representative of a foreign government, can do so. Once a US license exam is passed, licensing is possible in as little as a few days to a week. A US mailing address is required for application purposes. Information about US licensing is available on the ARRL Web site. If a US license is held, no other reciprocal operating authority may be used. It is possible that you may have more privileges if operating under CEPT, IARP. or on the basis of a Reciprocal Operating Agreement if one has been signed with the US.
Why all the troubles obtaining a reciprocal license? Just take the FCC exam very easy and you don't need to proof any citizenship. Just need a pictured ID and another ID, may be pictured or not and pay the exam fees, it much easier.
The exams place are easy to find and almost everyday there's an exam and don't need to be in the same city or area code.
Also, could go all the way from Technician to Extra class in one seating/day.
Iwan – W7NZ
Accredited Volunteer Examiner for ARRL and W5YI group