1. How do I know if a SIM card is blocked?

It is not possible to tell for sure from the SIM Slot status or GoIP status if a SIM card is blocked. However, you can try to examine this problem as follows:

a) If a SIM card is valid and is inserted in a SIM slot, the slot status should show "Online". Please make sure that the status here is "Online".

b) Next, if the GSM channel Status shows "Logout"， this means that the allocated GSM channel cannot register to its GSM Service provider. This could means that the SIM card is blocked. You can also try to use a different IMEI to check if the IMEI is blocked instead of the SIM card. Please insert the SIM card to a normal cellphone to verify if the SIM card is working properly.

c) If the GSM channel status is "Login", but you cannot make outgoing calls via the GSM channel. You can try to make a call to the phone number of the SIM card to see if the service provider will prompt you with a voice message. The other option is to send a USSD command to the service provider and note the response.

d) If you still cannot determine if the SIM card is blocked, you can then try to use a cellphone to test the card or contact your service provider for further assistance.

2. What are the common techniques used to avoid SIM blocking by a GSM service provider?

The techniques described below are experience reported by our customers. You should think them as guidelines since different GSM service provider may use different techniques. You are welcome to reported us on a technique that is not discussed here.

a) Limit the talk time per day

b) Limit the talk time per call

c) Do not make consecutive calls (by disabling the GSM channel for a short duration)

d) Do not always use the same cell station to make calls

e) Move the SIM cards to different location from time to time

f) Always use the same IMEI when moving a SIM card to a different GSM channel - Use Slot IMEI instead of the default IMEI assigned to a GSM channel.