My friend was only given a transit visa (instead of a free tourist visa) by a disagreeable immigration clerk in Karachi. But from all I'd read, it would be ok because he should be able to get a 30-day visa extension once he was in Bangkok. He got 30 days when he entered at the airport, so we planned to get 30 more days via extension. Beware this is NOT the case. After making the long journey to the Government Center, they told him he could only get a 7-day extension for a transit visa. Maybe this is a new rule? I did a lot research and did not see this information anywhere. So, now he's stuck with having to pay a penalty to change his airline ticket and can't stay as long as he wanted to. So now he had to pay 835 baht for the transit visa (the tourist visa is free until 31 Mar 2011), and then he had to pay 1900 baht for a 7 day extension, and pay to change his air ticket. What a bummer!

One rarely sees the transit visa. Perhaps Karachi gives it because they can charge for it, but not for the tourist visa. Not very nice of them.

Incidentally, the transit visa is missing in my collection "Current stamps of visas, extensions, etc" and I'd be grateful if anybody could post a scanned copy.

There is no extension available for a transit visa - the seven days is an under review period to leave when you are not approved for an extension of stay.

Transit Visa Requirements

Purpose of visit

To transit to the country of destination (Category “TS”)

To participate in sport activities (Category “S”)

The person in charge or crew coming to a port, station or area in the Kingdom (Category “C”)

Validity of visa

The validity of visa is 3 months.

Period of stay

Travelers with this type of visa will be permitted to stay in Thailand for a period not exceeding 30 days for EACH entry, begin on the first date you arrive in Thailand

http://www.thai-la.net/visa/visa-transit.htm