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Building a Personal VoIP System

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Re: Building a Personal VoIP System

#131
post #14

Has someone good experience with a VoIP-Provider (not OVH or Sipgate) in Europe?

Do you have any specific issues with Sipgate? I only have a couple of numbers with them and don't use them much but am curious what their reputation is like.

I just saw that they might discontinue their starter plan[0] as they focus on business. I can understand that residential voip is pretty much dead.

[0] https://help.sipgate.de/hc/de/articles/4407798852113-sipgate...

Re: Building a Personal VoIP System

#132
post #117

Earlier quoted context omitted.

UDP is unreliable transport by specification , so I guess that if a network equipment such as a router cannot cope with the general workload, it would probably sacrifice UDP first without a second thought.

If you don't have any evidence, guessing that routers/modems prioritize IP packets based on the next protocol sounds like a conspiracy theory.

Huh? It's an obvious thing to do. If you have to drop a packet because your queues are full, any engineer with an IQ over 50 will pick the victim from the UDP packets, because the sender expects it might happen, and also because it won't necessary cause a retransmission - e.g. an RTP packet.

Re: Building a Personal VoIP System

#133

Ah good memories! Even though I knew nothing about VoIP I installed, years ago, one at my wife's little SME using "RasPBX" (a distro made of Raspbian + FreePBX + Asterisk) running on a... Raspberry Pi 1 (maybe a Pi 2 but I'm pretty sure it was a 1). The Pi was booting from the SD card but everything was running on an external HDD. I did put six Cisco VoIP phones and all was working fine as long as no more than four p…

I have a tangentially related problem I have been battling with that you may be able to help me with. I'm moving overseas (Australia to Denmark) and would like to keep my current mobile phone number working for calls and SMS , but use it from afar. I would be able to leave a raspberry pi at a friend's house. Can you use this setup without a SIP provider? Would you need to buy a modem for the raspberry pi?what would y…

I use Callcentric for this. Ported a land line over years ago. It now has SMS which I can do using the Callcentric app. And it forwards voicemails to me with email. Otherwise I don’t use that line for actual calls anymore.

Re: Building a Personal VoIP System

#134
post #107

> SIP was initially released in 1999, and was designed with the assumption that each device has its own globally routable public IP address. After all, the IPv6 standard was released back in 1995, and NAT would soon be a thing of the past…right? Unforunately, this did not end up being the case. AFAIK, most residential and commercial ISPs these days do assign customers both a dynamically-DHCP-leased IPv4 address , and…

A lot of people expect a stateful firewall blocking incoming connections on their local network. Applying the same NAT system that is used for IPv4 to IPv6 is probably the best way to get this layer of security. Now in theory most devices should be safe to connect to the internet. But how many Internet of Shit devices are there in the average household that probably shouldn't be trusted? Crappy security cameras with…

> Applying the same NAT system that is used for IPv4 to IPv6 is probably the best way to get this layer of security.

...why? Routers have (stateful) firewalls, entirely separate from their NAT-ing abilities. You can still have the firewall without the NAT. (And the protocols that IoT devices rely on, like UPnP, are technically protocols for manipulating firewall rules, not NAT port-forwarding rules; so they still work fine without NAT in place.)

> But how many Internet of Shit devices are there in the average household that probably shouldn't be trusted?

I'm not sure about IPv4, but in IPv6 a given single logical interface can acquire multiple IPv6 addresses — meaning that your laptop or phone will have both a public global IPv6 address, and a link-local fe80:: IPv6 address. And things like multicast, DHCP discovery, etc. will only be attempted or accepted through that link-local address.

Now imagine a router that combines that firewall rule, with a bit of logic to automatically assign devices that join the AP, to separate VLANs, depending on their MAC address vendor part. So laptops and phones go on the "home" VLAN, while IoT devices go on the "sandboxed" VLAN. Where these VLANs are peered, but with stateful firewall rules between them: "sandboxed" devices don't get to speak to "home" devices, unless the "home" device speaks to them first; and multicast packets from "home" devices won't reach "sandboxed" devices.

In other words, a home-network gateway-router should have all the same defaults that an IaaS-tenant VPC does: nodes on the network have public-routable IPs; but all inbound ports to them are closed unless a device asks; and traffic flowing between those devices can only be seen by other devices intentionally put into that same VLAN, not by other "tenants" who happen to be sharing the same pipes.

Re: Building a Personal VoIP System

#135

> Use a SIP Application Layer Gateway. This is a horrible feature offered by some routers. Basically, it deep-packet-inspects your SIP traffic, rewrites the headers, and creates port forwards on-the-fly to make sure the inbound audio stream makes its way to your device. SIP ALGs are a total hack and notoriously buggy. Yes, these hacky ALG features also allowed internet users to access internal IPs on arbitrary servic…

This was on by default on a consumer router that was used at a small office. Their VoIP phones would get phantom calls until I discovered this and disabled it.

I'm pretty sure you've solved a mystery I was confused by years ago, back when I was doing tech support.

It wouldn't have mattered much because the router/modem combos in use didn't have a switch for SIP ALG anyway, bit it's good router finally know what could've caused the phantom phone ringing.

Re: Building a Personal VoIP System

#136
post #107

> SIP was initially released in 1999, and was designed with the assumption that each device has its own globally routable public IP address. After all, the IPv6 standard was released back in 1995, and NAT would soon be a thing of the past…right? Unforunately, this did not end up being the case. AFAIK, most residential and commercial ISPs these days do assign customers both a dynamically-DHCP-leased IPv4 address , and…

A lot of people expect a stateful firewall blocking incoming connections on their local network. Applying the same NAT system that is used for IPv4 to IPv6 is probably the best way to get this layer of security. Now in theory most devices should be safe to connect to the internet. But how many Internet of Shit devices are there in the average household that probably shouldn't be trusted? Crappy security cameras with…

> A lot of people expect a stateful firewall blocking incoming connections on their local network.

Totally! That's why that's the default setting for almost every router out there.

> Applying the same NAT system that is used for IPv4 to IPv6 is probably the best way to get this layer of security.

No? The default firewall rules will work just fine.

> So maybe keeping the stateful firewall by default is the best option.

Agreed. That's why routers ship with fully-closed firewalls for both IPv4 and IPv6. Incoming connections need firewall exceptions, either manually or through UPnP depending on how you've configured your network.

In fact, because of NAT issues like NAT slipstreaming, an IPv6 firewall is even more closed off than any IPv4 firewall that needs to let through FTP(S), SIP, and many other protocols depending on both sides of the connection using IPv4 as designed.

Re: Building a Personal VoIP System

#137
I have been tinkering with a personal VoIP system in my spare time over the last couple of months. At this point, I have rescued the 3 lines of house wiring in my 1970s house and connected them to Asterisk on a VM via a Cisco MC3810 and a Adit 600 channel bank. This has involved messing with T1s which was a childhood dream of mine. I have 12 phones connected to the system, using my house wiring, a few point-to-point wires, and some SIP VoIP phones over ethernet. In turn these connect to Phreaknet, C*NET, and of course the normal PSTN via a pair of different ITSPs. I now feel almost qualified to build an early 2000s business voice phone system, for what very little that is worth. More importantly, I have a rotary phone on my desk. ;)

Re: Building a Personal VoIP System

#138

Earlier quoted context omitted.

I've been using a voip number for all my sms 2fa needs for the last 5 years while living abroad. I have a dozen banks and other financial institutions plus the irs happily accepting it. Some companies, like openai, wont accept it, for those I just buy single use SMS numbers.

I've had problems with a bunch of places, so it's at least YMMV then. And I'd be wary of transferring an existing number in (as opposed to getting a new voip number and then setting it up). I'm sure specific services are hit or miss - there really shouldn't be a problem sending SMS to whatever number a user enters, but paternalistic snake oil salesmen gonna be paternalistic. I've had the least difficulty with Google…

I use a RedPocket (GSMA Flavor) $60/year for my resume and 2FA number as an eSIM.

I turn it on when needed, which is almost never. When not job searching, the voicemail plays the classic "this line has been disconnected" tones and message on repeat for two minutes. WiFi calling means I can use it anywhere I have WiFi.

I get incredibly few spam calls using this strategy.

Re: Building a Personal VoIP System

#139

Earlier quoted context omitted.

Same here. 3 businesses, only 1 problem in 10 years. The only thing I have to add: if you need to make telephone calls, the call quality using a SIP phone is much better than using a softphone.

This isn't necessarily true, a computer can speak SIP too, with a good headset it's just as good.

I disagree. Yes, in theory, an agent is an agent, but in practice I have never in my life at any point seen computer hardware that comes anywhere close to the usability of a Polycom device.

Re: Building a Personal VoIP System

#140

my wife had a requirement: be able to have an intercom for the house and shed. We used to have a baby monitor, but that was one way, for one room. Now we need many more rooms to talk to each other. I looked at some intercoms on amazon/ebay, they are all RF and a bit shit. I saw some wifi ones, but nothing cheap enough to take a punt on. I did think about trying to make something with an ESP32, but that would be too h…

I hope you ran optical between the house and the shed. The difference in ground potential among buildings can cause a lot of trouble for copper/electrical connections.
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