You don't need to replace anything in your telephone. Sometimes it is not possible to do without parts - but this is a sign of a transitional technology. DVD-players, for example, are not good technologies until DVD disks become widely available. Electric lights are not good technology if they require non-standard light bulbs. Programs which require complicated start-up routines are not as good as those which start with a single command.
Good technology is personalized .
One of the things which makes a telephone useful is that you have your own telephone number. In a similar manner, email is useful because you have your own email address. Bank machines would not be at all useful unless they opened your bank account - and only your bank account. Some of the simplest technologies succeed because they are personalized. Personalized housing is made possible with personalized keys, another good technology.