My attempt to find an answer to this via Google has failed hence asking the almighty STW collective.

I use voice activation on my iPhone to call people hands-free. It’s particularly handy in the car since I can do it directly from my Bluetooth headset without touching the phone.

I recently moved from my iPhone 4 to a 5, which of course has Siri. I quite like Siri, but it appears to need an internet connection, even if all I want to do is call someone from my contacts. This works using non-Siri voice activation, but not using Siri. This is a pain if I’m trying to let the missus know when I’ll be back but I’ve got no internet connection.

The question is, can I keep Siri turned on but still have access to non-internet reliant voice activation?

No internets, no Siri.

What you need to do is go to Settings > General > Siri > Off.
This will then default back to voice control which doesn’t use the internetz. 😉

So no, you cannot keep Siri on and use voice control, as Siri is voice control with a whole bunch of other features.

Siri essentially captures the voice pattern and transmits it via interwebz to some external processing I believe to get answers which is why it probably doesn’t work.

As said, turn Siri off. You can turn her back on when drunk and wanting to ask her the meaning of life though 🙂

Turning it on and off erases all that it’s learnt about your voice pattern, so not an ideal solution. This is directly from Apple’s Siri FAQs

If you like, you can reset what Siri has learned about your voice by turning Siri off and then back on in Settings > General > Siri.

Looks like it’s one or the other then.