I can ping my iPad

OK, this may not seem that hard. After all, it is networking. But the mobile networks make this a nightmare, so finally being able to actually ping my iPad is a huge step forward.

We finally have data SIMs that have unfettered IP connectivity (if only for a single static IPv4 address for now). No session tracking. No firewall. No NAT. Just raw IP. Networking like what it should be, in'it.

What is fun is that even when "turned off" (well, the blank screen mode one normally leaves it in) it seems to maintain the data connection indefinitely. And you can ping it! It does take a few seconds to respond initially so I can only assume the radio side is shut down to something that exchanges data every few seconds at most - though once you get through all the queued pings reply and it works.



  1. Yes, UMTS(WCDMA) knows 4 Radio Resource Control (RRC) states: DCH, FACH, PCH and idle.
    What you see is most likely the 'idle' behaviour followed by an transition to DCH or FACH.

    A friend of mine wrote his thesis about exactly that topic. The RTT's he saw in 'idle' were >2s. The timers are imposed by the network, so YMMV.

  2. Interesting. My involvement in original GSM specification was before packet data was added, but I guessed they would have something like that.

  3. A rather delayed comment, but just got my AAISP data SIM today, and I can ping my Galaxy Tab too! And run a web server on it! http://twitpic.com/347xgl

    So cool having a real Internet connection even on 3G...