Logging in and creating an account are done the same way:

• enter the number with which the account is/was created

• enter the code you receive via SMS or phone (if the SMS does not arrive, you may be called by a "+44" number in some cases)

Has the telephone number linked to this account changed? Then read the Change the phone number article.

No code received?

• first try a second time as there can be delays

• check in your phone if the numbers used by Bsit (8128, 8810, 8989,...) are blocked (Android: open the "Phone" app, tap "More", then "Settings", then "Blocked numbers" / iPhone: go to "Settings", tap "Messages", then "Blocked")