I have US Charles Schwab accounts and love them but don't have any experience with an international account. I asked them prior to applying for my Thai retirement visa if I could us a Thai address and they told me I would need to convert to an international account. I have a US virtual address so did not convert the account. I also have a skype US phone number and even though I am not able to receive text messages Schwab will do an automated phone call for One Time Passwords.
If you find out if there are any differences in the International account compared to the US accounts can you please share them.