Just done a bit of sim swapping (sounds a bit rude!) and I am totally surprised.
Firstly my unlocked VODEM could not see the telecom network to register on, so I could not use the Telecom SIM on the Vodem. I need to do some more thinking on that one.
Secondly, put my Vodafone sim into the T-Stick, set up the network parameters, and it connected first time! So no unlocking needed. Thank you Telecom!