Today the meaning would be completely different. A contemporary composition including a recording of a cellphone ringtone of an old-fashioned phone would be playfully ironic. A composition with a pre-programmed Nokia or T-Mobile or whatever ringtone would lack the melancholic atmosphere, and mainly be product placement. And it would kind of miss the point to be waiting longingly by the phone for a lover who finally calls to the tune of a number one single by Shakira.
As it's likely possible to download a ringtone for any of the above telephone songs, some cheeky producer might pull off the postmodern chicken-and-egg stunt of incorporating the ringtone of a given song into that same song. But I think we can probably say that the day of telephone rings in pop songs is over.