Transfer process is between different registrars so a. Same Hosting Company is NOT REQUIRED As an example if you have to transfer a domain from enom to Pubdomains Each registrar has a different interface, so if someone has to transfer from enom to Pubdomains - you first have to make a request at Pubdomains, Pubdomains in turn would send request to admin contact at enom to authorize the change. Admin (Domain Owner) at enom would accept the change (authorize the change) and then the domain gets transferred from enom to Pubdomains. There are intermediate steps like entering EPP code or similar authentication codes, but as I mentioned - depend from registrar to registrar! HTH