Phone modems (software + hardware) are very expensive to develop and only inexpensive to purchase because of the staggeringly high volumes and the fact that the

Phone modems (software + hardware) are very expensive to develop and only inexpensive to purchase because of the staggeringly high volumes and the fact that they are highly integrated. This is the main reason why the number of suppliers as massively dwindled: Large upfront investments are needed and only recouped if you manage to sell 10s if not 100s millions of units.