If Signal stop requiring telephone number, its popularity might skyrocket. The scheme is easy: to prevent spamming, you can have a pool of registered numbers th

If Signal stop requiring telephone number, its popularity might skyrocket. The scheme is easy: to prevent spamming, you can have a pool of registered numbers that are NOT associated with accouts. This is enough to check if a number is already in use. That's all we need! (almost. subjective. required, but not limited to.)