That's true that ISPs and WISPs can't really use Stripe (many use Adyen), but pure-VOIP companies offering hosted PBX and such are welcome at Stripe based on feedback I received from several people who work at Stripe.
When I asked Stripe Support about servicing VoIP companies last year they referred me to the prohibited businesses section and said:
"Historically we have seen that the telecommunications industry is one with too high of a likelihood of customer chargebacks. These need not necessarily be chargebacks in fact; the likelihood of potential chargebacks is also a deciding factor in our deliberations."
That's true that ISPs and WISPs can't really use Stripe (many use Adyen), but pure-VOIP companies offering hosted PBX and such are welcome at Stripe based on feedback I received from several people who work at Stripe.
SignalWire too should be able to use Stripe.