What size SIM does the GX400 and GX440 use? Both the SIM enabled versions of the device (GX400 for HSPA+ and GX440 for LTE) use a standard size SIM, which is 2FF. Category: General M2M Question ← FAQs Share this Article..emailFacebookDiggTwitterTumblrStumbleUponRedditPrintPinterestLinkedin