3550 Secure SMPP - User Port | Service Name:ssmpp

3550 is a User Port. Transport Protocol TCP UDP , 3550 Service Name ssmpp, Service Name Description: Secure SMPP.

Port	Protocol	Service Name	Description	Source
3550	TCP UDP	ssmpp	Secure SMPP	IANA
3550	TCP UDP	ssmpp	Secure SMPP	bekkoame

Port	Service Name	Description
706	silc	SILC
912	apex-mesh	APEX relay-relay service
1055	ansyslmd	ANSYS - License Manager
4595	ias-paging	IAS-Paging (ANRI-ANRI)
5413	wwiotalk	WWIOTALK
5595		Unassigned
5669		Unassigned
6245		Unassigned
7239		Unassigned
7374		Unassigned

A port is an endpoint of communication in an operating system. While the term is also used for hardware devices, in software it is a logical construct that identifies a specific process or a type of service.

Port numbers are assigned in various ways, based on three ranges: System Ports (0-1023), User Ports (1024-49151), and the Dynamic and/or Private Ports (49152-65535);

The Well Known Ports are assigned by the IANA and on most systems can only be used by system (or root) processes or by programs executed by privileged users. Ports are used in the TCP [RFC793] to name the ends of logical connections which carry long term conversations. For the purpose of providing services to unknown callers, a service contact port is defined. This list specifies the port used by the server process as its contact port. The contact port is sometimes called the "well-known port". To the extent possible, these same port assignments are used with the UDP [RFC768]. The range for well-known ports managed by the IANA is 0-1023.
DYNAMIC AND/OR PRIVATE PORTS Registered Ports are those from 1024 through 49151.
The Dynamic and/or Private Ports are those from 49152 through 65535