What Time Does Your Satellite Phone SIM Card Expire?

If you have an Iridium or Inmarsat IsatPhone Pro satellite phone and are using a prepaid airtime card from GMPCS you already know about the expiration date. But did you know that the official expiration date for a SIM card is at 00:00:00 Greenwich Mean Time (GMT) or Coordinated Universal Time (UTC)? Or that Iridium always uses GMT and Inmarsat UTC. For our purposes, there is no difference between the two indicators.


Because of this, you will need to be aware of the time zone where you are located and whether or not Daylight Savings Time (DST) is in effect where you are or in the United Kingdom (UK). Why the UK? For the answer you will need to think back to your primary school experience where we learned that the Prime Meridian was located at Greenwich, England. All satellite communications service activations, deactivations and expirations are based on GMT/UTC time.


So what does this mean for you? Well, if you are in the US Eastern time zone and daylight savings time is in effect for both the US and UK, your time will be 4 hours behind GMT. For example: 10:00 PM GMT will be 6:00 PM EDT.


Now if your prepaid SIM card expires on October 10th at 00:00:00 GMT, you will need to purchase additional airtime or a 30 day extension from GMPCS BEFORE 8:00 PM on October 9th. You may be saying to yourself, “That’s just crazy!!”, and a first glance it would seem so. But then we need to remember that satellite airtime is based on GMT and for that reason, we will need to leave reminder notes for ourselves to top-up our prepaid airtime cards in advance of the published expiration date/time.


To be safe, give yourself a 24 hour window and mark the expiration date on your calendar each time you add airtime, it will save headaches in the future and prevent the loss of unused airtime. We also recommend that you Google the current UTC time and act accordingly.


Any questions regarding the expiration of your SIM or available time extensions can be answered by calling GMPCS at 954-973-3100 or via email at: contact@gmpcs-us.com