There are lots of dictation apps on the App Store for free or very low cost. You can then use your iPhone to dictate anywhere, sending your files back to base by phone or WiFi. Your transcriptionist may only need to convert* te files to mp3 or similar, then play them in Express Scribe or FTR software with our USB pedal and they’re up and running. What could be simpler?
NCH Software - writers of Express Scribe - have an iPhone dictation app called Express Dictate, complete with insert mode, which can automatically create a compressed file and email it for transcription; more details at the App Store on your iPhone. The app is currently (25.9.14) free, though v.5.8 seems to be causing distress to long-time users.
There are other dictation / recording apps on the App Store too, so there is plenty of choice - go to the App Store and choose dictation or voice recorder. Check the file format that the app creates and whether Express Scribe can play it immediately, and whether it’s easy to convert it into a supported format.
* older versions of Express Scribe could play m4a files natively, but the latest ones can't. Use Switch to convert m4a to mp3 or other file.