GPRS IP Networking

recursv at recursv at
Mon May 19 08:59:05 CEST 2008

In my experience, the IP addresses are Nat pooled. But this is definatly carrier dependant.
 What they tend to do is to open a hole in the firewall and leave it open for 2-3 min without activity and then close it. So what I do is send keep alives (1 byte packets will do) every 90 seconds. This keeps the address and makes sure that they don't charge you for opening a new connection. 

Sent from my BlackBerry® wireless handheld

-----Original Message-----
From: Brandon Kruse <admteamkruz at>

Date: Mon, 19 May 2008 00:33:14 
To:List for Openmoko community discussion <community at>
Subject: Re: GPRS IP Networking

Either way, you could write a simple program on the phone to keep  
connecting to an end point (server) and give the server reverse access  
(stunnel) back to the device.

Just what I'm thinking :)

Brandon Kruse

On May 18, 2008, at 8:22 PM, "Steven Kurylo" <sk at>  

> Does someone know how IP addresses are handed out on the cellular
> network?  Do they give each phone an IP address, or do they do NAT?  I
> want to know if I'll be able to connect to my freerunner over GPRS,
> say I wanted to ssh into it.
> I've been searching the internet and haven't found an answer.  I
> connected to my website with my blackberry and saw different IP
> addresses for different requests; makes me think they have an outgoing
> NAT pool.  Of course this could also be carrier dependent.
> Thanks.
> -- 
> Steven Kurylo
> _______________________________________________
> Openmoko community mailing list
> community at

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