Where does the ISatPhone Pro work?

Posted in Globalstar, Handheld, Inmarsat, Iridium, Operators, Services at 8:46 am by timfarrar

One of the most interesting questions about Inmarsat’s new ISatPhone Pro is how well it will work at low elevation angles, including for example whether the phone antenna needs to be pointed towards the satellite. This is going to be particularly relevant in Alaska, much of which lies very close to the nominal edge of coverage, and well outside the 20 degree elevation angle contour (where Inmarsat suggests that “more user cooperation is required”), as shown below.

However, I’ve been told by Inmarsat that the phone is performing better than expected, even at relatively low elevation angles, so it will be interesting to see what this means in practice. Given that the beams used for registering the phone on the Inmarsat satellite are lower power than the beams used for a call, it appears probable that either the phone will register successfully and then calls can be made OK, or the phone won’t register and then no calls can be made at all.

Its surprising that we haven’t yet seen any published real world tests of the Inmarsat phone in comparison to Iridium, similar to the Frost & Sullivan reports which compared Iridium and Globalstar in 2008 and 2002. However, I’m sure similar analyses will be undertaken by both Iridium and Inmarsat at least for their own internal purposes, and possibly even for external publication if they believe the results are favorable. If you’ve tried out the phone in “fringe” coverage areas then feel free to let us know about your experience in the comments section below.

UPDATE: So now Frost & Sullivan has released its comparison of the Iridium and Inmarsat phones, which was commissioned by Iridium. It is notable that in Anchorage, Alaska, Frost & Sullivan “was unable to make or receive a call despite dozens of attempts and was only able to briefly find a satellite”. This points to difficulties with registration, as we suspected. However, Inmarsat sources tell us that it is perfectly possible to register on the satellite in Alaska, and make calls there. We haven’t yet got an independent view, but it would seem likely that the actual answer may lie somewhere between these two opposing views. We would speculate that you will probably have to have a pretty good idea where the Inmarsat satellite is so you can point the phone antenna at it during registration (maybe using a compass would be helpful?).


  1. abvillian said,

    September 21, 2010 at 3:23 am

    After I tried Terrestar Genus service I started using IsatPhone Pro as an anchor for my dinghy.



  2. timfarrar said,

    September 22, 2010 at 3:06 pm

    According to the TerreStar Quick Start Guide (http://www.terrestar.com/inc/pdf/GENUS_Quick_Start_Guide.pdf):

    To improve the quality of your satellite call, follow these guidelines:
    • Keep the device in the position with the strongest satellite signal.
    • Use a wired headset to make sure the back of the device remains in clear view of the southern sky.
    • Maintain the line of sight between the satellite and the device.
    • Do not put the device in your pocket or bag.
    • Maintain your position during the call.

  3. Brengelmann said,

    June 7, 2011 at 8:25 pm

    I’ve used the IsatPhone Pro in Dutch Harbor and Anchorage. In Dutch, I worried that I’d have to stay pointed to the satellite, but that was not the case, I was able to continue my call regardless of pointing. The phone worked in Anchorage near the airport without much “user intervention.”

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