% APNIC found the following authoritative answer from: whois.apnic.net

% [whois.apnic.net]
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% Information related to '103.23.156.0 - 103.23.159.255'

% Abuse contact for '103.23.156.0 - 103.23.159.255' is 'hm-changed@vnnic.vn'

inetnum:        103.23.156.0 - 103.23.159.255
netname:        VIETNAMOBILE-VN
descr:          Vietnamobile Telecommunications Joint Stock Company
descr:          6th floor, No7 Chua Boc, Dong Da, Ha Noi
country:        VN
admin-c:        HMH14-AP
tech-c:         NVM3-AP
abuse-c:        AV273-AP
status:         ALLOCATED PORTABLE
mnt-by:         MAINT-VN-VNNIC
mnt-lower:      MAINT-VN-VNNIC
mnt-routes:     MAINT-VN-VNNIC
mnt-irt:        IRT-VNNIC-AP
last-modified:  2020-06-16T04:30:39Z
source:         APNIC

irt:            IRT-VNNIC-AP
address:        Ha Noi, VietNam
phone:          +84-24-35564944
fax-no:         +84-24-37821462
e-mail:         hm-changed@vnnic.vn
abuse-mailbox:  hm-changed@vnnic.vn
admin-c:        NTTT1-AP
tech-c:         NTTT1-AP
auth:           # Filtered
mnt-by:         MAINT-VN-VNNIC
last-modified:  2025-11-17T23:08:34Z
source:         APNIC

role:           ABUSE VNNICAP
address:        Ha Noi, VietNam
country:        ZZ
phone:          +84-24-35564944
e-mail:         hm-changed@vnnic.vn
admin-c:        NTTT1-AP
tech-c:         NTTT1-AP
nic-hdl:        AV273-AP
remarks:        Generated from irt object IRT-VNNIC-AP
abuse-mailbox:  hm-changed@vnnic.vn
mnt-by:         APNIC-ABUSE
last-modified:  2020-05-13T04:20:41Z
source:         APNIC

person:         Hoang Minh Hai
address:        VIETNAMOBILE-VN
country:        VN
phone:          +84-24-35730123
e-mail:         hai.h@vietnamobile.com.vn
nic-hdl:        HMH14-AP
mnt-by:         MAINT-VN-VNNIC
last-modified:  2017-11-12T07:43:02Z
source:         APNIC

person:         Nghiem Van Minh
address:        VIETNAMOBILE-VN
country:        VN
phone:          +84-24-35730123
e-mail:         minh.nv@vietnamobile.com.vn
nic-hdl:        NVM3-AP
mnt-by:         MAINT-VN-VNNIC
last-modified:  2017-11-12T07:45:29Z
source:         APNIC

% Information related to '103.23.159.0/24AS38247'

route:          103.23.159.0/24
descr:          VIETNAMOBILE-VN
origin:         AS38247
mnt-by:         MAINT-VN-VNNIC
last-modified:  2022-03-03T12:22:33Z
source:         APNIC

% This query was served by the APNIC Whois Service version 1.88.34 (WHOIS-AU4)