smpplib.exceptions.UnknownCommandError: Unknown SMPP command code "0x3177" #189

from flask import Flask, request
from sms.reciever import receive_question, Sms_Answers
import sys
import smpplib.gsm
import smpplib.client
import smpplib.consts
import smpplib
import json, requests,  datetime
from models.create.model import Survey, Section, Section_Item, Question, Variant

app = Flask(__name__)
client = smpplib.client.Client('ip', port)

client.set_message_received_handler(
  lambda pdu: receive_question(pdu))


if client.state == smpplib.consts.SMPP_CLIENT_STATE_CLOSED:
    client.connect()
    client.bind_transceiver(system_id='system', password='pass', allow_unknown_opt_params=True)

@app.route("/", methods = ['POST'])
def send():
    who = request.json.get('who', -1)
    text = request.json.get('text', -1)

    if who == -1 or text == -1:
        return "Not accepted", 400
    
    parts, encoding_flag, msg_type_flag = smpplib.gsm.make_parts(text)

    for i in who:
        for part in parts:
            pdu = client.send_message(
                source_addr_ton=0,
                source_addr_npi=1,
                source_addr='source',

                dest_addr_ton=1,
                dest_addr_npi=1,
                destination_addr=i,
                short_message=part,
                registered_delivery=True,
                data_coding=encoding_flag,
                esm_class=msg_type_flag,
            )

    return "Done", 200