Nowadays, mobile is the most popular device in life. A mobile has many features to help people so almost of them have at least one mobile. People can use a mobile for keeping in touch with everyone, entertainment, working, etc. Therefore, many applications are developed on mobile, and it needs more testers to do the testing on mobile. There is a big problem while testing on mobile that is the tester cannot make a call on mobile. There are many reasons caused this problem.

Firstly, the important reason is the mobile account has no more money. So, it should be checked after making a call failed. In Vietnam, the number to check the account often is *101#, there should be a message to tell the user how much money they have had in their account. Almost of mobile providers, when making a call without enough money, there is a notice to notify user that the money in their account is not enough to make a call, and they advise the user to pay a card to make a call and send message.

Secondly, the network connectivity is also a reason. Sometimes, the SIM card cannot be detected, or the mobile network cannot be searched and connected. For checking this, the tester should observe the wave column on mobile to make sure that the mobile network is connected. If not, the tester should remove the SIM card and re-enter it again to kick the SIM card. In another way the tester needs to borrow another mobile, and put the SIM card in it to make sure that the SIM card works normally. This can be used to check if the SIM card is broken or it is relating to device’s problem.

Finally, if checking with the above problem and find out that the real reason is mobile’s problem. The tester should need to make sure that the mobile cannot detect any SIM card of any mobile provider. It is easily to fix when the tester find out which part of mobile is damaged.

In conclusion, there are many others problem caused that the mobile cannot make a call, but three above reason are the common reason. So, it is fixed easily when finding out the reason caused the problem. After that, the tester can use the mobile for the testing normally.