Sure, I connect via a semi PB, lcgfx, lmax, and IB. All of which allow execution at the most competitive spreads. All provide very good connectivity either via FIX or multi-language API hooks. If you are serious about currency trading and especially want to algorithmically trade then I highly recommend you to consider brokers that enable access to competitive markets WITHOUT spread mark-up. (Oanda significantly marks up the spread).
both, but mainly some I utilize for higher frequency strategies focused on currencies, only, while via IB I run mainly mid-frequency strategies and a several discretionary books.