SNCF also ordered Alstom Prima locomotives for its Transilien department, operating the (sub)urban railway network around Paris (Ile-de-France / IDF). Unlike all other Prima 1 types, the Transilien machines are equipped for passenger services, able to run 160 kph and to be used in push-pull services.

For the distant future, the SNCF keeps the possibility open to convert its IDF-Prima's to 'normal' BB 27000 machines for freight service; The rakes the BB 27300s are pushing/pulling right now, will be withdrawn earlier than the locomotives and most likely trainsets will replace them.

Note that the serie is designeted BB 27300, but that machines are actually numbered 827300. This is because the French number system adds a prefix to the service numbers which tells us for which department of the company the machine is running. SNCF Transilien (Ile de France) uses prefix 8.