Virtual Roaming Systems for GSM, GPRS and UMTS: Open Connectivity in PracticeeBookVirtual Roaming Systems for GSM, GPRS and UMTS: Open Connectivity in PracticekaryaArnaud Henry-LaborderePenilaian: 5 dari 5 bintang5/5Simpan Virtual Roaming Systems for GSM, GPRS and UMTS: Open Connectivity in Practice untuk nanti