First 2 months are free on the promotional offer. You can port your number but it must be done when you get the SIM so get it ready before you go to the CPW. Number porting cannot be done if you order online.
No cashback, just two months free to start with.https://www.talkmobile.co.uk/home.php?section=1&page=0
It uses vodaphone network.
Contract Length 30 days SIM only
Inclusive Texts to Talkmobile users
500 free texts
Inclusive International calls & texts
International calls & texts from the UK
to 60 countries included in the monthly bundle
512 KB included monthly