Cursed ethernet!

erm, my phone uses RJ11 - it won't talk to ethernet. (Though I'm aware that SIP ones do).

It uses unshielded twisted pairs though, which is what he actually said. Nothing to do with ethernet...

Not a balun, that is a balanced to unbalanced transformer. Both the phone and the cabling are balanced.

In the UK the ringing capacitor and "out of service" resistor.

Skype is a proprietary format not standards compliant VOIP. I think all conversations on Skype go through Skype servers. With VOIP the call setup procedure establishes a direct connection between the bits of internet facing VOIP equipment at each end.

This was not true when it was designed. It was a real peer-to-peer protocol which used central servers only for authentication and location. Much like SIP. However, since its aquisition and re-working by Microsoft this appears to be no longer the case. Of course the NSA has to tap everything.

Only in theory. In practice, when connecting a telephone to a VOIP provider and calling others on the telephone network, all traffic is via the provider's servers.

Is this why Microsoft replaced peer-to-peer working with a client-server one just so the NSA and GCHQ have a central point to tap into? The new MS song: Croak, croak.

My first ADSL modem/router badge "Sweex" had a 4 port switch, all of which would only work with a crossover cable when connecting to a NIC, and had to have a straight cable when connected to another switch!

Totally weird, but once I realised what was going on I just lived with it.

What Andrew is saying is strucrured cabling is just 4 twisted pairs, if you choose to use them for Ethernet, fine, but another common scenario is to use just a single pair of the cable for a POTS telephone. An adapter is used at the patch panel to put the phone line via the RJ11 onto the centre pair (blue/white usually) of the CAT5 and a second adapter at the wallplate presents he line back as an RJ11 socket.

I imagine in the US there would be a temptation to forego the adapters and plug the RJ11 directly into the RJ45 socket, not a terribly good idea, because the shutter in the wallplate tends to jam the plug in.

Here in the UK we have a dedicated telephone connector.

So do we!

It's design was the basis for the RJ-45.

RJ11 will plug into an RJ45 socket though... and with structured wiring the socket is only "ethernet" if you choose to patch the socket to a network switch at the comms hub.

No, but it can work over a structured CAT5 cabling network. You just break out a pair from the 4 in the rj45 plug, usually pair #1, and make/buy a cable with rj45 in one end and rj11 in the other.

Structured cabling systems are used for a lot more than ethernet. Token Ring, ISDN BRI and PRI, T1s, E1s, analog and proprietary digital phones (like Nortel and Siemens digital handsets), even arcnet has adapters for cat5 nowadays.

This is layer zero in the OSI model.

-- mrr

Skype is often peer to peer - when possible. What makes it not possible is some really tight firewalls, NAT gateways, etc. but in-general, if it's possible, it's peer to peer.

Naturally, what's logged is the "metadata" - caller, callee, IP addresses, time & date, but it would not surprise me in the least if the "agencies" could "tap" a Skype call by simply flagging it to be passed via MS's servers rather than peer to peer, regardless of the endpoints abilitys to do direct peer to peer...

It is possible to do peer to peer SIP calls and certianly IAX is designed to use peer to peer too, when possible, but NAT does make it a real PITA to make work reliably. (And then there's DTMF signalling )-:

It is one thing that Skype gets right - most of the time - becuse they started from scratch and didn't have 100 years of legacy behind them. If only SIP had done the same... SIP was also developed at about the same time as NAT - when people thought NAT was just a stop-gap. That was in the mid-late 90's... 15+ years ago now...

Gordon

Not where I worked in the late '90s - All the phones had baluns - at least that was what the techies called them.

Hm, why would those firewalls require voice traffic to pass skype servers? The firewalls could be pinholed by the 2 peers. The servers would only be used to set that up.

That's certainly how SIP works.

AFAICT

You make a call. you contact SIP central who tells you what endpoint to direct a call to. That might be its gateway, or it might be an IP address.

you connect to the supplied endpoint.

The supplied endpoint is able to receive VOIP from ANY address.

Cant answer for skype - never used it.

And if there were a standard for poking holes in firewalls (bearing in mind that there's NAT to think of too, for people on second-class connections) then that might work.

The reason Skype became popular in the first place was that it included a load of extremely dodgy firewall- and NAT-bypassing code (borrowed from KaZaA) to make it work well for non-technical people on those second-class connections.

(uPnP came too late for all this, and is a horrible security hole anyway.)

Boys! This is an international forum; not your-local-village-football- club. You read about the bloke who wanted to take his rPi down to Mexico: then he could just plug it into the TV at the hotel? The RCA is good. Do any of you kiddies know about the UK's ?

Gradually, it's unfolding to me what audience the rPi originators aimed at: most uk inet-users have a network. Like the blokes who've got a 4x4 to drive to the supermarket? Smart-arses eventually hit be economic reality.

I have WRONGLY been thinking i.t.o. a minimalist OLPC type project. Especially when I read about rPis going up in baloons.

VOIP as in SIP generally puts the VOIP gateway outside of the NAT anyway.

Or you organise passthrough.

The point of the SIP server is to associate whatever REAL IP address you are on as a publicly accessible thing, and a port, with a telephone number.

Not to mediate the VOIP packet transfer.

I certainly do... My Spectrum has an ethernet card and is connected to my LAN though lol :p

Which one? I worked on a friend's ZX80, then bought a ZX81, followed by a Spectrum 48K with two microdrives.

By the way, the Sinclair computers may have had an RCA socket on it's TV modulator, but it connected to a TV's antenna socket, not a composite video like the Pi (and most other equipment with RCA video out).

Should have read the FAQ. It was aimed at schools. Classrooms where there is an Ethernet LAN. Besides, for school use you just need one up-to-date SD card image, them duplicate it enough times for all the kids. You don't need any of this obscure G3 mumbo jumbo with diverse chipsets and weird drivers.