6.2 Troubleshooting

For the most frequently asked questions refer to faq.2n.cz.


  • The IMEI fails to change in the case of SIM card replacement. The IMEI change requiring SIM card fails to report itself.
    • Make sure that the GSM modules support IMEI change.
    • Make sure that valid IMEI change licences are available.
  • The SIM cards fail to assign to the GSM modules.
    • Try the hardsim mode for assignment or make sure that the GSM module is in the testing mode.
    • Check the validity of the rules.
  • The SIM cards assign to the GSM modules but fail to log in.
    • Make sure that the NAT settings in the IP Routers allow the SIM card stream pass from the SB to the SC without problems.
    • If you have USIM, try to change the SIM cache type setting on the SB.
    • Check the protocol error rate in the GSMs – QoS of SIM connection section.
    • Make sure that the signal intensity and frequency are sufficient on the GSM gateway installation site.
  • The system features a low ASR value.
    • Make sure that your SIP Proxy does not send a count of GSM calls higher than the GSM gateway capacity.
    • If a frequent SIM card change is set, reduce the maximum count of calls via the GSM gateway – the GSM modules are temporarily unavailable for standard calls while being in the process of recharging (especially the IVR type), virtual incoming calling or SIM replacement.
  • The system shows a low ACD value.
    • Make sure that the SIM card credit and validity check is set correctly – lower ACD may result from incoming call forwarding to the IVR services informing of a low credit, etc.
  • The IMEI file cannot be imported.
  • The IMSI/SCID file cannot be imported.
    • The SIM card database is watched according to the IMSI/SCID codes. The records that contain the IMSI/SCID code of the currently assigned SIM card will only be imported.
  • The simulation of incoming calls with 2N® SIM Star Server does not work.
    • Make sure that the take-over of SIM card records from 2N® SIM Star Server is enabled for the GSM gateway.
    • Make sure that this data transfer is enabled in 2N® SIM Star Server (SIM Server / Connections / IMSI/Phone distribution).
    • Check whether the GSM gateways have access to IP port 12349 in the event of connection via the NAT Router.