This is the 14207th most frequent German word.
gültige
Valid
The word 'gültige' is used as an attributive adjective here, qualifying the noun 'Telefonnummer' to indicate that the phone number is valid or legitimate.
Die gültige Telefonnummer ist im System gespeichert.
The valid phone number is saved in the system.
'Gültige' again functions as an attributive adjective describing 'Fahrkarte,' implying that the ticket must be valid or up to date for travel.
Ohne eine gültige Fahrkarte darf man nicht mitfahren.
Without a valid ticket, one is not allowed to travel.
Here 'gültigen' is the declined form of 'gültig' used with the masculine noun 'Ausweis' in the accusative case, signifying an ID that is currently valid or acceptable.