Trying to set up new iPhone - two-factor identification not coming through Ipad

Trying to set up a new iPhone and not getting a two-factor authentication code on my iPad. Tried sending a text to my phone number that also goes to my iPad (old - only on 9.9 version of an update) and nothing comes through. However, when I signed into my apple account on my computer, a two-factor code came through on my iPad. Any ideas?