Fitting sim card in portable wifi/mifi

How do you register a new sim card in the above unit , as it wants to send a code to register a new card

mifi things often have a control panel you log in to where you can see texts that have been sent to the SIM in your browser. if you can't figure out how to do that you'll have to put the sim in a phone first to activate it, then move it to the mifi

My SIM (pay monthly) was operational as soon as it was in the wifi/mifi but I couldn't complete the registration to allow the account to be managed online as the device (did not have SMS capability
Lebara told me they did not have a workaround to complete SIM registration, advised I should use some other device. I ended up sticking the SIM in an old phone to complete the registration. Whilst 3G has been turned off, the old phone received the SMS via 2G.
The SIM is back in the mifi, working fine on 4G, and the account is properly registered.
All Good