Why are there blocked TCP ports on my mobile Internet?

[VALNAR]

I've noticed that I cannot connect to services on non-standard ports.  For instance, an HTTPS server is normally port 443.  If I change it to 444, it does not connect anymore on my iPhone 6s through my data plan.  If I go on WiFi, it works fine.

Why is Verizon blocking some TCP/UDP ports on the Internet from our devices?  How can I get this block lifted?

[Ann154]

You need to research how Verizon Wireless assigns their ip addresses. A search of this community should yield results.

[VALNAR]

I'm not sure how they assign my IP matters.  Whether I get an IPv6 or NAT'ed behind an IPv4, outbound connections still work fine to most web servers and public resources.  I'm not requesting anything inbound.  If they allow 80 and 443 out, why wouldn't they allow 444 or 445 out?  What else doesn't work?

[Ann154]

John_Getzke

What are the restrictions for the private NAT firewall used by Verizon Wireless again?

[John_Getzke]

The NAT operated by VZW is a mystery.  It should be assumed that anything under a custom or non well known port will be disabled by default under VZWs NAT firewall policy. 

The cheapest way to work around custom ports and port forwarding requirements is to VPN into a network that allows you access to those resources.  You wont get VZW to make any kind of changes to their NAT on your behalf.  Not unless you purchase a static IP from them for $500.  With a Static all of the custom configuration options will apply as your device will no longer rest behind VZWs NAT.

[smith6612 · Accepted solution]

So Port 445 is supposed to be blocked, as this is normally used by SMB File Sharing. That's not supposed to be reachable on the public Internet. Port 444 is also the Simple Network Paging Protocol, something which pagers can use to receive messages, but as it's Telnet-based VZ is likely blocking it to prevent awful things from happening, except perhaps on pager only plans.

Other than that, at least on a check of my phone, it seems most other protocols not tied to a local network file sharing or management port are open. Even the common ports used for Steam, Torrents, or Tor are open on the outbound.

Just note that VZ runs a transparent proxy for HTTP Traffic. So there might be some inconsistencies if you're doing any web development and expect content to appear a certain way. Also be aware that HTTP headers sent to web servers are messed with by Verizon as a result.