Problems getting large text

[mukhammad-akilov]

If a user sends a large text then SMSC divides the message into several parts. When I receive these parts, the short_message field of the pdu object contains Buffer value instead of String value.
Example:

{ params:
   { service_type: '',
     source_addr_ton: 1,
     source_addr_npi: 1,
     source_addr: '992901000895',
     dest_addr_ton: 0,
     dest_addr_npi: 1,
     destination_addr: '502',
     esm_class: 64,
     protocol_id: 0,
     priority_flag: 0,
     schedule_delivery_time: '',
     validity_period: '',
     registered_delivery: 0,
     replace_if_present_flag: 0,
     data_coding: 0,
     sm_default_msg_id: 0,
     sm_length: 140,
     short_message: <Buffer 05 00 03 90 08 06 40 61 79 19 e4 2e df 41 f4 37 28 ff ae bb 40 d2 72 98 9c 76 9f 41 54 74 19 34 7e bb e9 65 3c 1d f4 36 83 c2 72 7a
7a cc 2e cf 59 a0 ... > },
  tlvs: {},
  isResp: [Function],
  cmdLength: 188,
  cmdId: 5,
  cmdStatus: 'ESME_ROK',
  seqNr: 9,
  cmdName: 'deliver_sm' }
2018-09-26T11:15:37Z [inf] larvitsmpp: lib/session.js: session() - socket address: 10.241.208.181:2775 - deliver_sm() - TLV message_state is missing. SeqNr: 10
--------------------------------------
{ params:
   { service_type: '',
     source_addr_ton: 1,
     source_addr_npi: 1,
     source_addr: '992901000895',
     dest_addr_ton: 0,
     dest_addr_npi: 1,
     destination_addr: '502',
     esm_class: 64,
     protocol_id: 0,
     priority_flag: 0,
     schedule_delivery_time: '',
     validity_period: '',
     registered_delivery: 0,
     replace_if_present_flag: 0,
     data_coding: 0,
     sm_default_msg_id: 0,
     sm_length: 140,
     short_message: <Buffer 05 00 03 90 08 07 40 74 74 98 0e 0a cb cb 20 77 f9 0e a2 bf 41 f9 77 dd 05 92 96 c3 e4 b4 fb 0c a2 a2 cb a0 f1 db 4d 2f e3 e9 a0 b7
19 14 96 d3 d3 63 ... > },
  tlvs: {},
  isResp: [Function],
  cmdLength: 188,
  cmdId: 5,
  cmdStatus: 'ESME_ROK',
  seqNr: 10,
  cmdName: 'deliver_sm' }
2018-09-26T11:15:37Z [inf] larvitsmpp: lib/session.js: session() - socket address: 10.241.208.181:2775 - deliver_sm() - TLV message_state is missing. SeqNr: 11
--------------------------------------
{ params:
   { service_type: '',
     source_addr_ton: 1,
     source_addr_npi: 1,
     source_addr: '992901000895',
     dest_addr_ton: 0,
     dest_addr_npi: 1,
     destination_addr: '502',
     esm_class: 64,
     protocol_id: 0,
     priority_flag: 0,
     schedule_delivery_time: '',
     validity_period: '',
     registered_delivery: 0,
     replace_if_present_flag: 0,
     data_coding: 0,
     sm_default_msg_id: 0,
     sm_length: 36,
     short_message: <Buffer 05 00 03 90 08 08 40 f4 32 9e 0e a2 a3 c3 74 50 58 5e 06 b9 cb 77 10 fd 0d ca bf eb 2e 90 b4 1c 26 a7 dd 67> },
  tlvs: {},
  isResp: [Function],
  cmdLength: 84,
  cmdId: 5,
  cmdStatus: 'ESME_ROK',
  seqNr: 11,
  cmdName: 'deliver_sm' }