If I understood well, once the modem is attached the connection i.e. acquiring the bearer channel is straight-forward. With HL7588 it seems that this is not working (most of times).
I have used AT commands and MBIM to make a stable procedure for RAW-IP connection. However it seems the modem fails to acquire the bearer channel (time out is 15 seconds) most of the times:
max command size : 512
openning device for the session.
sending open message.
sending : 16 bytes
header_type : 0x0001
header_length : 0x0010
header_transaction : 0x0001
00000000 01 00 00 00 10 00 00 00 01 00 00 00 00 02 00 00 ................
reading : 16 bytes
header_type : 0x80000001 MBIM_MESSAGE_TYPE_OPEN_DONE
status_code : 0x0000 - success
header_length : 0x0010
header_transaction : 0x0001
00000000 01 00 00 80 10 00 00 00 01 00 00 00 00 00 00 00 ................
sending : 48 bytes
header_type : 0x0003
header_length : 0x0030
header_transaction : 0x0002
00000000 03 00 00 00 30 00 00 00 02 00 00 00 01 00 00 00 ....0...........
00000010 00 00 00 00 A2 89 CC 33 BC BB 8B 4F B6 B0 13 3E .......3...O...>
00000020 C2 AA E6 DF 01 00 00 00 00 00 00 00 00 00 00 00 ................
reading : 264 bytes
header_type : 0x80000003 MBIM_MESSAGE_TYPE_COMMAND_DONE
command_id : 0x0001
status_code : 0x0000 - success
header_length : 0x0108
header_transaction : 0x0002
00000000 03 00 00 80 08 01 00 00 02 00 00 00 01 00 00 00 ................
00000010 00 00 00 00 A2 89 CC 33 BC BB 8B 4F B6 B0 13 3E .......3...O...>
00000020 C2 AA E6 DF 01 00 00 00 00 00 00 00 D8 00 00 00 ................
00000030 01 00 00 00 01 00 00 00 01 00 00 00 02 00 00 00 ................
00000040 3F 00 00 00 03 00 00 00 01 00 00 00 08 00 00 00 ?...............
00000050 00 00 00 00 00 00 00 00 40 00 00 00 1E 00 00 00 ........@.......
00000060 60 00 00 00 3C 00 00 00 9C 00 00 00 3C 00 00 00 `...<.......<...
00000070 30 00 31 00 34 00 37 00 36 00 39 00 30 00 30 00 0.1.4.7.6.9.0.0.
00000080 30 00 31 00 34 00 33 00 30 00 37 00 37 00 00 00 0.1.4.3.0.7.7...
00000090 4D 00 32 00 4D 00 5F 00 37 00 31 00 36 00 30 00 M.2.M._.7.1.6.0.
000000A0 5F 00 41 00 54 00 54 00 5F 00 4D 00 42 00 49 00 _.A.T.T._.M.B.I.
000000B0 4D 00 5F 00 44 00 45 00 42 00 55 00 47 00 5F 00 M._.D.E.B.U.G._.
000000C0 57 00 57 00 5F 00 30 00 31 00 2E 00 58 00 4D 00 W.W._.0.1...X.M.
000000D0 4D 00 37 00 31 00 36 00 30 00 5F 00 56 00 31 00 M.7.1.6.0._.V.1.
000000E0 2E 00 31 00 5F 00 4D 00 42 00 49 00 4D 00 5F 00 ..1._.M.B.I.M._.
000000F0 4E 00 41 00 4E 00 44 00 5F 00 41 00 44 00 41 00 N.A.N.D._.A.D.A.
00000100 50 00 54 00 5F 00 52 00 P.T._.R.
devicetype : 0x0001 - embedded
cellularclass : 0x0001
voiceclass : 0x0001 - no-voice
simclass : 0x0002
dataclass : 0x003F
smscaps : 0x0003
controlcaps : 0x0001
maxsessions : 0x0008
deviceid : 014769000143077
firmwareinfo : M2M_7160_ATT_MBIM_DEBUG_WW_01.
hardwareinfo : XMM7160_V1.1_MBIM_NAND_ADAPT_R
mbim_end has been called.
>>>>>>>>>>>>>> pinstate
max command size : 512
sending : 48 bytes
header_type : 0x0003
header_length : 0x0030
header_transaction : 0x0003
00000000 03 00 00 00 30 00 00 00 03 00 00 00 01 00 00 00 ....0...........
00000010 00 00 00 00 A2 89 CC 33 BC BB 8B 4F B6 B0 13 3E .......3...O...>
00000020 C2 AA E6 DF 04 00 00 00 00 00 00 00 00 00 00 00 ................
reading : 60 bytes
header_type : 0x80000003 MBIM_MESSAGE_TYPE_COMMAND_DONE
command_id : 0x0004
status_code : 0x0000 - success
header_length : 0x003C
header_transaction : 0x0003
00000000 03 00 00 80 3C 00 00 00 03 00 00 00 01 00 00 00 ....<...........
00000010 00 00 00 00 A2 89 CC 33 BC BB 8B 4F B6 B0 13 3E .......3...O...>
00000020 C2 AA E6 DF 04 00 00 00 00 00 00 00 0C 00 00 00 ................
00000030 03 00 00 00 01 00 00 00 05 00 00 00 ............
required pin : 3 - pin2
remaining attempts : 5
mbim_end has been called.
>>>>>>>>>>>>>> attached ?
max command size : 512
sending : 48 bytes
header_type : 0x0003
header_length : 0x0030
header_transaction : 0x0004
00000000 03 00 00 00 30 00 00 00 04 00 00 00 01 00 00 00 ....0...........
00000010 00 00 00 00 A2 89 CC 33 BC BB 8B 4F B6 B0 13 3E .......3...O...>
00000020 C2 AA E6 DF 0A 00 00 00 00 00 00 00 00 00 00 00 ................
reading : 76 bytes
header_type : 0x80000003 MBIM_MESSAGE_TYPE_COMMAND_DONE
command_id : 0x000A
status_code : 0x0000 - success
header_length : 0x004C
header_transaction : 0x0004
00000000 03 00 00 80 4C 00 00 00 04 00 00 00 01 00 00 00 ....L...........
00000010 00 00 00 00 A2 89 CC 33 BC BB 8B 4F B6 B0 13 3E .......3...O...>
00000020 C2 AA E6 DF 0A 00 00 00 00 00 00 00 1C 00 00 00 ................
00000030 00 00 00 00 02 00 00 00 20 00 00 00 80 F0 FA 02 ........ .......
00000040 00 00 00 00 00 E1 F5 05 00 00 00 00 ............
nwerror : 0x0000 - unknown
packetservicestate : 0x0002 - attached
uplinkspeed : 50000000
downlinkspeed : 100000000
mbim_end has been called.
>>>>>>>>>>>>>> already attached
>>>>>>>>>>>>>> connect to network
Thu Oct 10 19:33:38 UTC 2019
max command size : 512
connect
protocol : ipv4v6
access point name : ltemobile.apn
sending : 136 bytes
header_type : 0x0003
header_length : 0x0088
header_transaction : 0x0005
00000000 03 00 00 00 88 00 00 00 05 00 00 00 01 00 00 00 ................
00000010 00 00 00 00 A2 89 CC 33 BC BB 8B 4F B6 B0 13 3E .......3...O...>
00000020 C2 AA E6 DF 0C 00 00 00 01 00 00 00 58 00 00 00 ............X...
00000030 00 00 00 00 01 00 00 00 3C 00 00 00 1A 00 00 00 ........<.......
00000040 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000050 00 00 00 00 00 00 00 00 03 00 00 00 7E 5E 2A 7E ............~^*~
00000060 4E 6F 72 72 73 6B 65 6E 7E 5E 2A 7E 6C 00 74 00 Norrsken~^*~l.t.
00000070 65 00 6D 00 6F 00 62 00 69 00 6C 00 65 00 2E 00 e.m.o.b.i.l.e...
00000080 61 00 70 00 6E 00 00 00 a.p.n...
mbim message timeout
mbim_end has been called.
Thu Oct 10 19:33:54 UTC 2019
max command size : 512
connect
protocol : ipv4v6
access point name : ltemobile.apn
sending : 136 bytes
header_type : 0x0003
header_length : 0x0088
header_transaction : 0x0006
00000000 03 00 00 00 88 00 00 00 06 00 00 00 01 00 00 00 ................
00000010 00 00 00 00 A2 89 CC 33 BC BB 8B 4F B6 B0 13 3E .......3...O...>
00000020 C2 AA E6 DF 0C 00 00 00 01 00 00 00 58 00 00 00 ............X...
00000030 00 00 00 00 01 00 00 00 3C 00 00 00 1A 00 00 00 ........<.......
00000040 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000050 00 00 00 00 00 00 00 00 03 00 00 00 7E 5E 2A 7E ............~^*~
00000060 4E 6F 72 72 73 6B 65 6E 7E 5E 2A 7E 6C 00 74 00 Norrsken~^*~l.t.
00000070 65 00 6D 00 6F 00 62 00 69 00 6C 00 65 00 2E 00 e.m.o.b.i.l.e...
00000080 61 00 70 00 6E 00 00 00 a.p.n...
mbim message timeout
mbim_end has been called.
Thu Oct 10 19:34:10 UTC 2019
max command size : 512
connect
protocol : ipv4v6
access point name : ltemobile.apn
sending : 136 bytes
header_type : 0x0003
header_length : 0x0088
header_transaction : 0x0007
00000000 03 00 00 00 88 00 00 00 07 00 00 00 01 00 00 00 ................
00000010 00 00 00 00 A2 89 CC 33 BC BB 8B 4F B6 B0 13 3E .......3...O...>
00000020 C2 AA E6 DF 0C 00 00 00 01 00 00 00 58 00 00 00 ............X...
00000030 00 00 00 00 01 00 00 00 3C 00 00 00 1A 00 00 00 ........<.......
00000040 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000050 00 00 00 00 00 00 00 00 03 00 00 00 7E 5E 2A 7E ............~^*~
00000060 4E 6F 72 72 73 6B 65 6E 7E 5E 2A 7E 6C 00 74 00 Norrsken~^*~l.t.
00000070 65 00 6D 00 6F 00 62 00 69 00 6C 00 65 00 2E 00 e.m.o.b.i.l.e...
00000080 61 00 70 00 6E 00 00 00 a.p.n...