Why would they need the same port?
Instead, we're locked into proprietary platforms or relying on old phone systems.
No, there’s a reason software like FaceTime, and calling in general, are mediated by centralized services and implemented as client-server. Because relying on your users to have stable IP’s, and to always be behind a properly configured firewall, would be an utterly insane way to design something.
Hence “ipv6 is a relic of a bygone era”, because in the era we live in now, IP addresses change and users move between networks constantly, and NAT is very much the least of our problems.
You're pretty much never getting a new IP at every cell tower.
> Then I get to my friends house and his router is gonna block unestablished connections so you better call me soon.
PMP can solve that.
> Because relying on your users to have stable IP’s
Not a stable IP, but some kind of stable identity. Like a DNS name. That can be provided by someone like Apple, or Google, or whoever. It doesn't need to be ultra-centralized by only a single thing controlling it.
It gives you a public dynamic IP + port combination if your network is NAT1 all the way to the internet. Both IP & port being dynamic kinda complicates things, they ended up inventing a new DNS record type, "IP4P" where IPv4 address and port are encoded as an IPv6 address, and modified WireGuard/OpenVPN clients are required.
We are supposed to solve this using SRV records, but I don't think many consumer-facing apps can do this.
The topic of discussion right now is peer-to-peer software, which is the quintessential thing that is always lauded by ipv6 proponents as the killer app of ipv6, because each device has its own globally-routable IP.
But “what address do I send these packets to?” is like, 10% of the issue with designing p2p software. Users ip’s are always changing. They move around. They go behind firewalls that will block their traffic. They go behind firewalls they don’t have permission to reconfigure. This is the case in IPv4, and it will always continue to be the case even if we were 100% IPv6.
IPv4 can work today for p2p use cases if you don’t make the assumption that the port is static. But that’s like 1 of N assumptions you have to check if you’re writing peer to peer software. The other N of them are all still issues, even in IPv6.
So wouldn't it be nice to go ahead and solve that 10% of the problem instead of just limping along with it?
If you can avoid an explicit port, that can be nice. But anywhere you're using an IP, v6 without a port is longer than v4 with a port. An implicit port is only useful when you're using DNS. (And if you're designing a service, you can choose to use DNS records that contain the port.)