PrePaidGSM.net Forum (Archived) - View Single Post - How do sim4travel, maxroam etc. work technically?

torput · **How do sim4travel, maxroam etc. work technically? -** 14-04-2008, 11:51

What's the catch with all these "receive calls for free while roaming" SIM cards?

In other words, could someone please explain technically how they work. I know GSM techonlogy pretty well and there is something either fishy or very clever in these services. Somehow it utilizes SIM toolkit + GSM roaming number.

	(#1)
torput (Offline) Junior Member Newbie Posts: 2 Join Date: 14 Apr 2008 Country:	How do sim4travel, maxroam etc. work technically? - 14-04-2008, 11:51 What's the catch with all these "receive calls for free while roaming" SIM cards? In other words, could someone please explain technically how they work. I know GSM techonlogy pretty well and there is something either fishy or very clever in these services. Somehow it utilizes SIM toolkit + GSM roaming number.