# Why is this Telephone Adapter banned in the USA? **URL:** \ **Category:** Factual Questions\ **Created:** [July 31, 2018, 2:54pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869 "2018-07-31T14:54:12Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![No\_Wikipedia\_Cites](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@No\_Wikipedia\_Cites](https://boards.straightdope.com/u/No_Wikipedia_Cites)\ **Post date:** [July 31, 2018, 2:54pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/1 "2018-07-31T14:54:12Z")
[https://www.amazon.fr/Adaptateur-RJ45-PTT-femelle-0-20M/dp/B006WXPQ26](https://www.amazon.fr/Adaptateur-RJ45-PTT-femelle-0-20M/dp/B006WXPQ26) This RJ45 to PTT Female adapter is prohibited to be sold to the USA. Why is that? I imagine this is to allow a EU telephone to be connected to the USA network, but what would happen if this adapter would be used? WOuld it work? Break the phone? ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [July 31, 2018, 3:03pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/2 "2018-07-31T15:03:23Z")
The \* learn more\* link says the seller determines the countries they will ship to. Do you know that it shipping to the US is prohibited or is it just the seller’s choice? ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [July 31, 2018, 3:18pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/3 "2018-07-31T15:18:55Z")
UK seller that sells to the US > **[M.C.L MCL PTT-RJ45/C - cable interface/gender adapters (RJ45, PTT, Male/Female,...](https://www.amazon.co.uk/M-C-L-MCL-PTT-RJ45-interface-adapters/dp/B004VRJ2U2)** > > Buy EK (ebay) seller that sells to the US > **[MCL PTT RJ45 C cable interface gender adapters RJ45 PTT Male Female White | eBay](https://www.ebay.ie/itm/MCL-PTT-RJ45-C-cable-interface-gender-adapters-RJ45-PTT-Male-Female-White-/252988451452)** > > Find great deals on eBay for MCL PTT RJ45 C cable interface gender adapters RJ45 PTT Male Female White. Shop with confidence. Not having any idea what that actually is or being able to read (or translate) the french Amazon page, about all I can come up with is that you can get them shipped to the US, just not with that seller. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [July 31, 2018, 3:19pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/4 "2018-07-31T15:19:46Z")
What phone system do you expect this to work with? Normal “POTS” doesn’t use RJ-45s. ---
**Author:** ![Jasmine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jasmine/32/2964_2.png) [@Jasmine](https://boards.straightdope.com/u/Jasmine)\ **Post date:** [July 31, 2018, 3:29pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/5 "2018-07-31T15:29:36Z")
> [@beowulff](#): > > What phone system do you expect this to work with? Normal “POTS” doesn’t use RJ-45s. RJ-45’s are VoIP through a network. That’s what we have. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [July 31, 2018, 3:41pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/6 "2018-07-31T15:41:30Z")
> [@Jasmine](#): > > RJ-45’s are VoIP through a network. That’s what we have. Yeah, but this thing is too simple to do any data decoding. I’m not even sure what a PTT is (push to talk?). ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [July 31, 2018, 3:48pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/7 "2018-07-31T15:48:34Z")
> [@Jasmine](#): > > > [@beowulff](#): > > > > What phone system do you expect this to work with? Normal “POTS” doesn’t use RJ-45s. > > RJ-45’s are VoIP through a network. That’s what we have. Yes, you’d use an RJ-45 connector to connect a VoIP phone (like [one of these](https://www.cisco.com/c/en/us/products/collaboration-endpoints/unified-ip-phone-7900-series/index.html) from Cisco) to a network switch via a network port. But these phones are essentially computers. They are not at all POTS phones. ---
**Author:** ![vonespy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/vonespy/32/6204_2.png) [@vonespy](https://boards.straightdope.com/u/vonespy)\ **Post date:** [July 31, 2018, 3:52pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/8 "2018-07-31T15:52:21Z")
From what I can tell from that Amazon page, it looks like PTT must be an old-style phone jack / plug in Europe. This is a simple device that simply converts the PTT plug into a RJ45. If you’re expecting to use this with VoIP phones, I think you’re going to be really disappointed. ---
**Author:** ![Weisshund](https://avatars.discourse-cdn.com/v4/letter/w/ba8739/32.png) [@Weisshund](https://boards.straightdope.com/u/Weisshund)\ **Post date:** [July 31, 2018, 8:58pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/9 "2018-07-31T20:58:59Z")
RJ45 can be used for analog phones. But i do not think thats a thing in the US anymore as most multi line systems now are voip or some other digital means you you maybe still have a very old still functioning system. But you used to be able to get 4 line capable analog phones and it used an RJ45 and it was literally just 4 analog lines coming in. ---
**Author:** ![Cleophus](https://avatars.discourse-cdn.com/v4/letter/c/a88e57/32.png) [@Cleophus](https://boards.straightdope.com/u/Cleophus)\ **Post date:** [July 31, 2018, 11:04pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/10 "2018-07-31T23:04:07Z")
RJ-45 is just a connector type. It can be used for anything, and has been used for analog (POTS) telephones, digital telephones, Ethernet, serial ports, and all manner of ad-hoc and proprietary standards. VoIP phones operate over Ethernet. They are not analog lines that can be split up. It sounds like you came across the device in the OP while trying to add extra phones to a VoIP network. That’s not something you can do by yourself; extra phones need to be provisioned by the system’s administrators. ---
**Author:** ![icbm](https://avatars.discourse-cdn.com/v4/letter/i/2acd7d/32.png) [@icbm](https://boards.straightdope.com/u/icbm)\ **Post date:** [July 31, 2018, 11:39pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/11 "2018-07-31T23:39:03Z")
PTT is an abbreviation of Post, telegraph & telephone, aka the government agency that (used to) handle all those things. In french it would be “Postes, télégraphes et téléphones”. This thing would be more useful if it had RJ-11 on the end because you can fit one of those into an RJ-45 jack but not the other way around. I wonder if modern houses in France use RJ-45 everywhere and this is to allow someone to keep using an antique unit? ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [August 1, 2018, 1:02am UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/12 "2018-08-01T01:02:11Z")
RJ45 was originally a telephone service connector and France mandated RJ45 when they deprecated the F-010 or PTT connector in the mid 2000’s. All new construction in France has to use RJ45 for POTS service. While this was probably still in the hope of the rise of ISDN, which was rare in the US due to high inter-LATA tariff pricing, ISDN was expected to replace POTS in the late 2000’s when France made the switch. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [August 1, 2018, 5:56am UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/13 "2018-08-01T05:56:48Z")
> [@Cleophus](#): > > RJ-45 is just a connector type. Sorry, but no. My long-ago uncle Alexander and Ma Bell put huge amounts of money and time into designing all of this. Too much to say it’s just a connector. The RJ in RJ45 means Registered Jack. The connector is 8P8C, or eight positions, eight contacts. A plug carrying four analog phone lines would be an RJ61. Same exact 8P8C plug and jack, but a different spec and pinout. And not interchangeable. And to make things worse, there really is nothing officially called RJ45. RJ45S is a special 8P8C plug with an extra nubbin so it can’t be plugged into a non RJ45S jack. What people call RJ45 for computer networking is actually either T586A or most often, T586B. As for the PTT adapter, it looks like the one on Amazon UK has an RJ11 jack on the adapter itself and a short RJ11 to RJ45-ish cable, so if you had a French phone, you could toss the little cable and plug into a US POTS line, if you still have one. My experience with VOIP lines and ATAs (analog telephone adapter) is that it can be a bit hit or miss what will actually work. Rotary dial phones, as a general rule, will not work. ---
**Author:** ![Cleophus](https://avatars.discourse-cdn.com/v4/letter/c/a88e57/32.png) [@Cleophus](https://boards.straightdope.com/u/Cleophus)\ **Post date:** [August 1, 2018, 6:57am UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/14 "2018-08-01T06:57:32Z")
> [@gotpasswords](#): > > Sorry, but no. My long-ago uncle Alexander and Ma Bell put huge amounts of money and time into designing all of this. Too much to say it’s just a connector. The RJ in RJ45 means Registered Jack. The connector is 8P8C, or eight positions, eight contacts. A plug carrying four analog phone lines would be an RJ61. Same exact 8P8C plug and jack, but a different spec and pinout. And not interchangeable. > > And to make things worse, there really is nothing officially called RJ45. RJ45S is a special 8P8C plug with an extra nubbin so it can’t be plugged into a non RJ45S jack. What people call RJ45 for computer networking is actually either T586A or most often, T586B. > > As for the PTT adapter, it looks like the one on Amazon UK has an RJ11 jack on the adapter itself and a short RJ11 to RJ45-ish cable, so if you had a French phone, you could toss the little cable and plug into a US POTS line, if you still have one. My experience with VOIP lines and ATAs (analog telephone adapter) is that it can be a bit hit or miss what will actually work. Rotary dial phones, as a general rule, will not work. Yeah, you’re right. Technically RJ-45 is almost never used, but it’s so common to use the term RJ-45 that people will look at you weirdly and consider you a pedant if you say 8P8C. My point was that you can’t make determinations about what type of network is using the connection just by the connector type. ---
**Author:** ![No\_Wikipedia\_Cites](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@No\_Wikipedia\_Cites](https://boards.straightdope.com/u/No_Wikipedia_Cites)\ **Post date:** [August 1, 2018, 7:52pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/15 "2018-08-01T19:52:45Z")
Yes just to clarify, the goal would be to put a French analog rotary phone on a regular US telephone (RJ45) jack. Supposedly rotary phones are supposed to still be supported throughout the US. About VoIP I dont know a thing. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [August 1, 2018, 7:59pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/16 "2018-08-01T19:59:53Z")
Here is the French law that required rj45, or more specifically CIE 60603-7 for new construction. [https://www.orange.com/fr/content/download/3244/28356/version/1/file/STI01-ed080507.pdf](https://www.orange.com/fr/content/download/3244/28356/version/1/file/STI01-ed080507.pdf) It was not ISDN as I had guessed above, but the original intended Ethernet on pairs 2 and 3. While rj45 may be rare for phone systems in the US, it is a requirement in France. ---
**Author:** ![Alley\_Dweller](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alley_dweller/32/430_2.png) [@Alley\_Dweller](https://boards.straightdope.com/u/Alley_Dweller)\ **Post date:** [August 1, 2018, 8:37pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/17 "2018-08-01T20:37:06Z")
> [@No\_Wikipedia\_Cites](#): > > Yes just to clarify, the goal would be to put a French analog rotary phone on a regular US telephone (RJ45) jack. Supposedly rotary phones are supposed to still be supported throughout the US. About VoIP I dont know a thing. A regular US telephone jack is an RJ11. ---
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [August 2, 2018, 4:46pm UTC](https://boards.straightdope.com/t/why-is-this-telephone-adapter-banned-in-the-usa/818869/18 "2018-08-02T16:46:14Z")
> [@No\_Wikipedia\_Cites](#): > > Yes just to clarify, the goal would be to put a French analog rotary phone on a regular US telephone (RJ45) jack. Supposedly rotary phones are supposed to still be supported throughout the US. About VoIP I dont know a thing. Yes, rotary phones are still usable one the old phone networks. In fact you still need to turn on DTMF (touch-tone) in 5E and Genband switches. I’m not sure about DMS-100 switches, but I’d put down money that you do. Whether the IP-PBX that connects your VoIP phone to the network would understand the rotary pulses, I suppose would depend on the make and model, but I would not count on that. Added on edit: If your goal is to add this phone to your home phone system, you’ll want an RJ11 jack, as stated upthread. An RJ45 would not even physically fit.