[HOT] Using Wifi to make phone calls from mobiles using a router.

Thu Jan 11 17:42:26 UTC 2018

There's no mistery to cross a router, most apps use UPnP in their local app
to configure and keep open a routable port on the NAT router. Other
solutions have existed but now UPnP is almost uniersally supported by most
routers and users don't have to know their IP. Instead they renew their
subscription (as long as their local app is running and connected to the
Internet) to a directory server that will give routing info, and notably
the public IP and port number to use to reach a user behind a NAT. However
this is known to not work properly with some ISP's using "large NAT"
(notably for mobile users: mobile users are instructed by their FAI to use
their own telephony or VoIP service instead and pay their communications,
and other people will call them to their normal mobile phone number!)

So no it is not simple to make any direct peer-to-peer communication
without some third party service and specific configurations. An IP is no
longer sufficient (and many users now no longer have an IPv4, they are only
reachable via IPv6, and many IPv4-only users can't reach these IPv6 users
directly without a third party proxy).

Direct peer-to-peer communication will be possible for every one if every
one has an native IPv6 access (where NAT will no longer be needed: NAT over
IPv6 is devil, only a transitory solutions for those users that still have
only IPv4 connectivity and need to configure an external IPv6 proxy server
providing them a single IPv6 address instead of a block of size /48 at
least, where autoconfiguration allows setting a "permanently" routable IPv6
addesses for each app without using any NAT). So to perform a call in IPv6,
just can just connect to "[::<IPv6 address>]:<standard port for VoIP app>]"
and you no longer have to do any port number translations or configuration.

2018-01-11 12:12 GMT+01:00 Bjoern Hassler <bjohas+mw at gmail.com>:

> Hi John, Hi Philippe,
>
> Thanks for the post. I'd written this reply before Philippe posted, but
> not hit sent, sorry. Let me send it anyway.
>
> To explain further: Unless one router extends the network of the other,
> each phone would be behind a firewall created by the router. So you'd have
> to place the phone in the DMZ or port-forward on the router. Using
> https://en.wikipedia.org/wiki/CSipSimple might be especially helpful if
> you are doing point-to-point WiFi (without internet connection of either
> router). A "192.168.x.x" is network internal, so you won't be able to
> connect between "192.168.y.y". And even then, as Philippe points out, the
> address of the router may not be fixed.
>
> However, if the routers are connected to the internet, it would also be
> possible to use commercial VOIP apps (like WhatsApp, Hangouts, Skype). I am
> not sure how they route voice traffic these days, but Skype used to allow
> peer-to-peer, which like Hangouts/WhatsApp should mean "peer-to-peer when
> possible". In any case, for an app that just "handshakes" via the internet,
> and then can use peer-to-peer, only the connectivity between the routers
> matters. A nice feature would be if the app told you what it's doing (p2p
> or via server) so that you know whether you're safe on WiFi or killing the
> internet connection...
>
> There is an app called FireChat, that apparently can do p2p off-internet.
> It's proprietary, and I haven't looking into it much. However, it strikes
> me that such an app would be really useful, especially server-less, with
> the option to connect to a global network if available.
>
> Is there anybody who wants to form a little action group to investigate?
>
> Hope this helps!
> Bjoern
>
> On 10 January 2018 at 23:58, john whelan <jwhelan0112 at gmail.com> wrote:
>
>> The problem was mentioned some time ago in reference to a refugee camp in
>> Europe.
>>
>> You need csip simple and to know the phone's ip address.  IP checker is
>> a simple free app that will how this.
>>
>> "Just install csip simple and create a profile called "user", not linked
>> to any server. To call another person with the same setup, you just need to
>> know his ip address. Once they have sent it via voice, email, sms or
>> whatsapp or ever (much better) a safer way like textsecure, you simply type
>> "user at 15.14.173 et cetera (basically user@ other person's ip) and their
>> Csipsimple will ring. It works and it's the purest form of Internet. "
>>
>> It doesn't have to be called user by the way.  So John or Mabel will work
>> fine.  You do need the ip address so to call John it would be
>> John at 192.168.2.99 mabel at 192.168.2.33
>>
>> You do not need the router to be connected to the internet for this to
>> work by the way.
>>
>> Cut and paste should work.  So stick the wifi router up high and you
>> should be able to cover a fair range.
>>
>> Cheerio John
>>
>>
>>
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