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On Tue, 13 Apr 2010, Dan Dart wrote:
I will have to sue them. Mwuhahaha.I'm not being serious.However, I will strongly disagree with you when you say it's more reliable - and that's not just because I make money from selling SIP.
Well, it works for me, and SIP doesn't without messing around. I'm not saying connections are reliable, they drop off oftenYou do not need to mess about with NAT and port-forwards to make standards based VoIP work
Do show me how I can simply call someone and have it route.
Call who?And that's the issue. You want to call another SIP user for free, then you need a service provider who's acting as the registration server, and you both need to be using that provider - just like Skype, but rather than (ab)use random PCs/Servers to act as their registration servers (supernodes), it's slightly more controlled in that someone ownes it and it's deliberately being run for this purpose - and to run it costs money, which is why it's usually chargable!
You can use direct IP to IP dialling, (or enum), but that will fail because of NAT - Skype fails here too - which is what supernodes are for. Your data may go peer to peer, but before that it may need some 3rd party server to setup the call and make sure it can do peer to peer.
You want to call a standard telephone number? Sure - and there are dozens of people who'll hapilly take your money who do the plumbing to place outgoung calls to the PSTN. You want it for free? Sure - lookup betamax (no, not the video tape, but e.g. http://backsla.sh/betamax )
You want a new number for incoming calls? Again, easy, and sometimes it's free too - e.g. sipgate.co.uk (Although I wish I knew how they can offer it for free when I have to pay for my numbers!)
NAT is fairly well understood these days. It was developed round about the same time as SIP (late 90's) and unfortuantely the 2 never really talked to each other - each thinking the other would "go away", I suspect...
SIP encodes the IP address of the device into the data packet, so the far-end gets the IP address of the router, and inside the data packet, it has the IP address of the device (which is usually 192.168.x.y or other RFC1918 address) There are good reasons for it, and these are what usually upsets SIP and NAT.
The biggest headache I see these days is routers with a built-in "SIP ALG" - that's where the router think's it knows more about SIP then the phone or PBX does and tries to fix-up the SIP registration requests to the remote system. (deep packet inspection/mangling). Almost all of these are broken in some way or another, so turn it off if you can.
And do not use port forwarding for SIP endpoints behind a NAT router. Just use a STUN server in the phone, or hope that your ITSP is using an inteligent proxy to work out the NAT mangling and off you go. If you have a PBX, you may need port forwarding, but this then potentially stops independant phones registering to external SIP servers (not often needed in a business setting though)
who are these 3rd partys?3rd parties are unavoidable sometimes. If I could run my own, I would.
That's easy - just connect your PC to the Internet directly (use the DMZ host feature of your router), and allow it to become a supernode. Bingo. You're now routing calls for 1000's of others. Hope your broadband is uncapped...
But I don't have the time or resources and will just have to put up with being spied on. That's why I use Google, their services are goos, and I don't care what they do (though that may change soon due to secrets - but I can just use PGP)
What makes you think you are being spied on, or are you just paranoid? And have you any idea how utterly trivial it is to snoop existing analogue or digital PSTN connections? And if you're the govt. then extend that to mobile communications too... And soon to ITSPs if the govt du-jour gets their way...
And Skype is rumoured to have a back-door anyway. There were rumours of it being used in Italy (I think). If you want secure communiucations, establish a VPN to the other end....
Gordon -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html