http://www.3gpp.org/ftp/tsg_cn/wg1_mm-cc-sm/tsgn1_04/gprs_ad_hoc/tdocs/n1-99450.doc
roaming
http://www.arib.or.jp/english/html/overview/doc/STD-T63v9_60/5_Appendix/R99/23/23122-3a0.pdf
http://www.3gpp.org/ftp/tsg_cn/wg1_mm-cc-sm/tsgn1_04/gprs_ad_hoc/tdocs/n1-99450.doc
roaming
http://www.arib.or.jp/english/html/overview/doc/STD-T63v9_60/5_Appendix/R99/23/23122-3a0.pdf