RJ45 vs RJ11 vs RJ12 Connector, What is the Difference?

Have you ever seen a phone line plugged into the jack at the back of the phone through an RJ11 connector and a network cable plugged into the Ethernet on the wall through an RJ45 connector? What is the difference between RJ45 vs RJ11 connectors? What is the difference RJ11 vs RJ12? Which connector should we choose in different application scenarios?

This article will explore the distinctions between R45 vs. RJ11 and RJ11 vs. RJ12 connectors and their specific uses.

What is RJ45 Connector

RJ45 connectors are widely used in producing Ethernet cables, which can be made by terminating twisted pair cables with RJ45 connectors. RJ45 connectors are made of transparent plastic, which is crystal clear, so many people also call them “crystal heads.” Compared with RJ11 and RJ12 connectors, RJ45 connectors have different structures, with eight positions and eight gold pins.

What is RJ11 Connector

The RJ11 connector can be connected to a twisted pair cable and is often used to connect a telephone to a corresponding wall jack or other telephone line. It has 6 positions, 2 or 4 gold pins, usually four. The RJ11 locks into place by a locking tab, smaller than the locking tab of the RJ45. In exceptional cases, RJ11 connectors can also be used to build LANs.

RJ11 vs RJ12, What is the Difference?

• The wiring mode of RJ11 is 6P2C, i.e. 6-position 2-contact or 6P4C, i.e. 6-position 4-contact. However, the wiring pattern of RJ12 is 6P6C, i.e., 6 positions and 6 contacts.
• The RJ12 is relatively less popular than the RJ11. It is typically used for home phone lines and connecting modems, but only in large companies for centralized telephone networks.
• The RJ11 connector uses a flat telephone wire with four copper wires inside. In contrast, the RJ12 uses a flat telephone wire with six copper wires inside.
• The RJ11 connector can connect two phone lines, while the RJ12 connector can connect three.

Features	RJ11	RJ12
Full form	Registration jack 11	Registration jack 12
Structure	6P2C/P4C	6P6C
Connection	Two telephone lines	Three telephone lines
Popular	More popular	Less popular
Price	Cheaper	More expensive
Size	Smaller	Larger
Installation	It is more difficult to install due to its added weight and bulk.	It is simple and easy to install.
Weight	Lighter	Heavier
Speed	Up to 2Mbps	Up to 4Mbps, it can handle twice the amount of data as the RJ11
Application	Home corded telephone and modem connection	Centralized telephone layout for large enterprises,some specialized communication devices
Compatibility	The RJ11 connector cannot be plugged into the RJ12 jack	The RJ12 connector can be plugged into the RJ11 jack

RJ11 vs RJ12 Connector: How to Choose?

I can’t give you a definite choice because everyone’s selection is based on their needs. For home use, you should choose the RJ11 connector. However, if you only have RJ12 jacks in your house, the RJ11 connector can’t be plugged into the RJ12 jacks, and it will take time and money to re-install. If it is for company use and needs to unify the central telephone layout, RJ12 is recommended, but the price will undoubtedly be a little more expensive than RJ11.

RJ45 vs RJ11, What is the difference?

Structure difference: The RJ45 connector is an 8P8C connector with 8 notches and 8 contacts, while the RJ11 connector is a 6P4C or 6P2C connector with 6 notches and 4 or 2 contacts.

Different size: RJ45 is more significant because it has more notches than RJ11.

There are two wiring standards for RJ45 connectors: T568A and T568B.

The T568B standard is more commonly used than the T568A standard. Twisted-pair cables with the same wiring standard at both ends of the RJ45 connector are called straight cables. Twisted-pair cables with different wiring standards at both ends of the RJ45 connector are called crossover cables. For more information on the differences and application scenarios for these two types of cables, visit our article “What are Ethernet Crossover Cables?“

There is no wiring standard for RJ11, but common wiring is shown below:

Different applications: RJ45 connectors generally terminate network cables and connect computers, routers, switches, and other network equipment, while RJ11 crystal heads terminate telephone lines.

Bandwidth is different: RJ45 supports up to 10Gbps speed, while RJ11 supports up to 24Mbps speed.

Features	RJ45	RJ11
Full form	Registration jack 45	Registration jack 11
Structure	8PP8C	6P2C/P4C
Speed	Up to 40 Gbps	Up to 24Mbps
popular	Not as common as the RJ11	More generally
Price	More expensive	Cheaper
Size	Larger, rectangular	Smaller, square
Weight	Heavier	Lighter
Application	Switches, routers, laptops, PC, and other network devices	Landline telephones, ADSL lines, fax machines, and other voice devices
Compatibility	The RJ45 connector cannot be plugged into the RJ11 port	The RJ11 connector can be plugged into the RJ45 port(not suggested)
Wiring Standards	TIA/EIA-568-B standard	As long as both ends use the same wiring scheme, it will function correctly.

RJ45 vs RJ11 Connector: How to Choose?

There is no definitive recommendation for choosing RJ45 or RJ11, as individual needs and existing network facilities must be considered.

If you use it for data communications, such as connecting a computer, switch, or printer to a network, then you must choose an RJ45 connector. On the other hand, if the device is used for voice communications, such as a landline telephone, fax machine, or early broadband internet connection, then the RJ11 connector should be selected.

FAQ

Q: How many phone lines can be connected to RJ11 and RJ12?

A: The RJ11 1 has 4 wires inside that connect to two phone lines, and the RJ121 has 6 connected wires inside that connect to three.

Q: What is the difference between RJ11 and RJ45?

A: RJ45 is used with Ethernet cables to connect network devices; RJ11 is used with telephone cables to realize telephone communication.

Q: Is there much difference in appearance between RJ11 and RJ12?

A: In fact, the two appear similar. The main way to distinguish between the connectors is to look at the number of internal gold pins: RJ11 has 4 or 2, and RJ12 has 6

Q: RJ11 and RJ45, which connector size is more prominent?

A: The RJ45 is more extensive, and the RJ45 is smaller.

Q: What are the risks if I plug an RJ45 connector into an RJ11 jack?

A: The larger size of the RJ45 connector can damage the RJ11 jack, resulting in data loss or corruption.

Q: Do RJ11 and RJ45 connectors work with the same negative voltage?

A: RJ45 works at higher voltage, and RJ11 works at lower voltage.

Conclusion

Through this article, did you learn more about RJ11, RJ12, and RJ45 connectors? Try to observe them and see how they work. Each kind of connector has its significance. Maybe they will retire from the stage later when the times fall, but the constant is that they all contribute to our lives.