modem(esp32+sim800c) stopped after recieved a packet

[richardwuday]

board:esp32+sim800c,demo:Pppos_client,i found a problem:modem stopped after recieved a pcket,that will happen every time.This confused me. Is sim800c can't fit this demo? Can someone give some advice?here is the log:
start up:

[0;32mI (1141) pppos_example: GOT ip event!!![0m
[0;32mI (1151) pppos_example: PPP state changed event 266[0m
[0;32mI (1161) pppos_example: MQTT other event id: 7[0m

【2021-11-10 13:45:41:738】[0;32mI (2451) pppos_example: MQTT_EVENT_CONNECTED[0m
[0;32mI (2461) pppos_example: sent subscribe successful, msg_id=58484[0m

【2021-11-10 13:45:41:843】[0;32mI (2651) pppos_example: MQTT_EVENT_SUBSCRIBED, msg_id=10995[0m

【2021-11-10 13:45:42:048】[0;32mI (2811) pppos_example: MQTT_EVENT_SUBSCRIBED, msg_id=26615[0m
[0;32mI (2851) pppos_example: MQTT_EVENT_SUBSCRIBED, msg_id=58484[0m

【2021-11-10 13:45:54:633】[0;32mI (15351) pppos_example: MQTT_EVENT_DATA[0m
TOPIC=v1/dn/cmd

DATA={"taskId":15,"serviceIdentifier":"open_cmd","productId":15098425,"payload":{"open_request":6},"deviceId":"15098425TMB56E55443388"}


【2021-11-10 13:45:55:355】[0;31mE (16071) esp-modem: esp_dte_handle_line(114): handle line failed[0m
[0;33mW (16071) pppos_example: Unknow line received: ~!EH[0m

【2021-11-10 13:45:57:261】[0;32mI (17981) pppos_example: Modem PPP Stopped[0m
[0;32mI (17981) pppos_example: PPP state changed event 267[0m
[0;32mI (17981) pppos_example: PPP state changed event 265[0m
[0;32mI (17981) pppos_example: PPP state changed event 262[0m