RWA Letter SWIFT MT799
While the RWA Letter may be issued without a SWIFT message bank to bank, it gives stronger validity and strength to the applicant if they do so. If a SWIFT MT799 is not required a bank or trust can issue the Ready Willing and Able Letter by hard copy courier, by fax, Key Tested Telex, or by secure fax as the occasion may allow.
Source jamesdo.org