# Secure Terminal Equipment

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**Secure Terminal Equipment** (**STE**) is the U.S. government's current (As of 2008) encrypted telephone communications system for wired or "landline" communications. STE is designed to use [ISDN](/source/ISDN) telephone lines which offer higher speeds of up to 128 kbit/s and are all digital. The greater bandwidth allows higher quality voice and can also be utilized for data and fax transmission through a built-in [RS-232](/source/RS-232) port. STE is intended to replace the older [STU-III](/source/STU-III) office system and the [KY-68](/source/KY-68) tactical system. STE sets are backwards compatible with STU-III phones, but not with KY-68 sets.[1]

STE sets look like ordinary high-end office desk telephones and can place unsecured calls to anywhere on the [public switched telephone network](/source/Public_switched_telephone_network) (PSTN), as well as secured calls on it via the phone's backwards compatible STU-III mode. There is a [PC Card](/source/PC_Card) slot in the STE that allows a [Fortezza](/source/Fortezza) Plus ([KOV-14](/source/KOV-14)) Crypto Card or [KSV-21](/source/KSV-21) Enhanced Crypto Card to be inserted. When an [NSA](/source/National_Security_Agency)-configured Crypto Card is present, secure calls can be placed to other STE phones. STE phones are "releasable" (unlike STU-III sets). All cryptographic algorithms are in the crypto card.

Newer STE sets can communicate with systems that use the [Secure Communications Interoperability Protocol](/source/Secure_Communications_Interoperability_Protocol) (SCIP) (formerly Future Narrowband Digital Terminal (FNBDT)). There are upgrade kits available for older units.[2]

## Models

- **Office**: The Office STE is the most widely used STE and provides voice and data access to ISDN (Integrated Services Digital Network) and PSTN (Public Switched Telephone Network) telecommunications systems.
- **Tactical**: The Tactical STE is similar to the Office STE but can also access the TRI-TAC (TRI Service TACtical) network and has a serial EIA-530A/EIA-232 BDI ([Black](/source/Red/black_concept) Digital Interface) port.
- **Data**: The Data STE provides remote access for voice, fax, data and video-conferencing. This model has two serial EIA-530A/EIA-232 BDI ports and allows for data transfers to multiple destinations.
- **C2**: The C2 STE is similar to the Tactical STE but C2 has modified software for use with its Tactical Terminal Locking Handset mechanism.
- **STE-R**: Similar to the Data STE, the STE-R*emote* provides dial-in access to the [Defense Red Switch Network](/source/Defense_Red_Switch_Network) (DRSN).
- **VoIP**: The STE now has [Voice over Internet Protocol](/source/Voice_over_Internet_Protocol) (VoIP) capability, available as an upgrade to the current models, or built into some new models.

As of 2007, a typical STE terminal cost about $3,100, not including the crypto card.[2]

## References

1. ["Secure Telephone Unit Third Generation (STU-III) / Secure Terminal Equipment (STE)"](https://web.archive.org/web/20101209040001/http://www.fas.org/irp/program/security/_work/stu3.html). [Federation of American Scientists](/source/Federation_of_American_Scientists). Archived from [the original](https://fas.org/irp/program/security/_work/stu3.html) on December 9, 2010. Retrieved September 2, 2010.

1. ["STE: Secure Terminal Equipment: Direct Sale Pricing"](http://www.l-3com.com/cs-east/ia/ste/ie_ia_ste_sale.html). [Archived](https://web.archive.org/web/20061015185200/http://www.l-3com.com/cs-east/ia/ste/ie_ia_ste_sale.html) 2006-10-15 at the Wayback Machine.

## External links

- [The NAVY INFOSEC WebSite on STU-III and STE](https://fas.org/irp/program/security/_work/stu3.html) [Archived](https://web.archive.org/web/20101209040001/http://www.fas.org/irp/program/security/_work/stu3.html) 2010-12-09 at the Wayback Machine

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Adapted from the Wikipedia article [Secure Terminal Equipment](https://en.wikipedia.org/wiki/Secure_Terminal_Equipment) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Secure_Terminal_Equipment?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.