Нет, только в этих отделениях банка. Вот выдержка из квитанции
This deposit slip must be used to make your visa fee payment at the following Muscat Bankbranches before the expiration date, as noted above:
Shatti Al Qurm Branch
Salalah Main
Firq - Nizwa
Sohar Main
Head Office, Seeb
Ibra Main
Bureimi Main
More information about the branch locations can be found
athttp://www.ustraveldocs.com/om/om-loc-bank.asp