iphone 6 model A1586 sim free is the one for my int'l travel anywhere in the world. It supports: GSM, CDMA,LTE radio frequencies.
Apple’s iPhone 6 (Models A1549 and A1586) and iPhone 6 Plus (Models A1522 and A1524) both support four-band GSM, five-band CDMA2000, five-band UMTS (with HSPA+42 support), and sixteen LTE FDD bands (with support for up to 150Mbps of download speeds). The quad-band GSM and pent-band UMTS provide complete global coverage for GSM and UMTS/HSPA+ networks all over the world. The five CDMA2000 bands enable coverage on all CDMA carriers in the US (who use ESMR, Cellular 850MHz, AWS 1.7+2.1 GHz, and PCS 1.9GHz for CDMA), as well as KDDI in Japan (who use Cellular 850MHz and IMT 2.1GHz for CDMA) and China Telecom in China (who use Cellular 850MHz for CDMA). These bands are the same as the American Sprint model for the iPhone 5S and 5C.
For LTE FDD, the iPhones support a full mix of bands for every region. LTE bands 1 (IMT 2.1GHz), 3 (DCS 1.8GHz), 5 (Cellular 850MHz), 7 (IMT-E 2.6GHz FDD), 8 (Cellular 900MHz), 20 (EU 800MHz), and 28 (APT 700MHz) are supported to provide the full range of access to LTE FDD networks throughout Europe, Asia, and Brazil. LTE bands 2 (PCS A-F blocks 1.9GHz), 4 (AWS-1 1.7+2.1GHz), 5 (Cellular 850MHz), 7 (IMT-E 2.6GHz FDD), 13 (US Upper 700MHz C block), 17 (US Lower 700MHz B+C blocks), 25 (PCS A-G blocks 1.9GHz), 26 (ESMR+Cellular 850MHz), 28 (APT 700MHz), and 29 (US Lower 700MHz Supplemental Downlink) offer nearly full access to LTE FDD networks throughout the Americas. Japanese LTE bands 18 (ESMR+Cellular 850MHz subset) and 19 (Cellular 850MHz subset) are intended to enable KDDI and NTT DoCoMo’s low-band networks, while band 28 sits in the wings for future 700MHz LTE network rollouts by KDDI, DoCoMo, and SoftBank.