Since 15th March, 2009, ICANN requires gTLD Registrars to follow the Inter-Registrar Transfer Policy See details while processing Inter-Registrar Transfers. It is recommended that you go through the same, to acquaint yourself with its requirements.
There are instances where the transfer of a domain name might get stuck, and the Registrar has to perform certain steps to push it through. The possible problems and their solutions are mentioned underneath.