Here is a list of ports that Sprint block for inbound traffic.
TransPort routers use port 80 for web GUI management
TransPort routers use port 4000 for serial port access over TCP
 
•         Sprint blocks certain known IP ports to keep unauthorized traffic from entering the CDN
>    80 tcp http (web servers)
>    icmp echo request ping
>    445 tcp/udp NetBIOS shares / drive mappings / windows authentication
>    135 tcp/udp NetBIOS shares / drive mappings / windows authentication (Microsoft RPC portmapper)
>    137 tcp/udp NetBIOS shares / drive mappings / windows authentication
>    138 udp NetBIOS shares / drive mappings / windows authentication
>    139 tcp NetBIOS shares / drive mappings / windows authentication
>    4000 tcp
>    4899 tcp
>    1026 udp
>    1027 udp
 
There are others, but we can’t release the entire list, these are the main ports that may affect some customers.
Last updated: 
Jan 16, 2024