Existing mobile number to be changed to O2 with contract

I have completed my procedure for signing up with O2 as a new costumer, I have filled out the required electronic form today 25th October 2017.
When I was filling the form there was a place for the phone number, in which I filled out my current telephone number 0152xxxxxx27. This telephone number, however, is not from O2 service provider. it is Lycamobile. I would like to know if my telephone number will be changed or not, if so, then I must as for what should I do in order to make sure that my number stays the same. There weren't any information that clarified something on the matter while filling the form. Please kindly inform me on the matter. _____________Edit o2_Jessica:[i]Deleted the phone number. Data privacy.