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The frequently asked questions are here.
Please check before making inquiries.
Q. Is COMST SIM compatible with any mobile device?
A. It is compatible with smart phone, tablet, wifi router etc. Sim unlock is not necessary with a device supplied by ntt docomo. Sim unlock is necessary with a device supplied by softbank.
We have confirmed that following devices are compatible with COMST SIM. (Supported devices)
Q. Can we make a voice call or/and send a SMS?
A. The SIM is for data only. A voice call and SMS are not available.
Q. Can we use tethering function?
A. SIM free devices are available with tethering. However, due to limitations of carriers or devices, some models may not be available.
Q. Can I confirm APN settings or network connection of the SIM before visiting Japan?
A. Please set up APN and activate the SIM in Japan. A billing is started as of activation and valid date may be shortened.
Q. Can I leave the sim without activation?
A. Please activate the sim within 15 days from the date of purchase. It may not be able to use it afterwards.
Q. What is the rule of speed limitation of COMST unlimited plan?
A. High speed can be used until 300MB between 0:00 and 23:59. The speed is reduced to 128kbps afterwards. The data count is reset at 0:00.
Q. Can we confirm the remaining data?
A. It is referable by COMST app and at any time.
Q. Is any procedure needed for continuation use?
A. A continuation plan (recharge) can be purchased on COMST app and
Q. Is there any payment available except credit card?
A. We accept payment at convenience store besides credit card. The payment can be made 24 hours a day, seven days a week at designated convenience store nationwide.
Q. What procedure is needed to use the SIM continuously?
A. If you recharge between the day the plan is finished and the charge expiration date, you can continue using it. The charge expiration date can be confirmed on COMST app and
Q. How does the charge expiration date set?
A. If you recharge between the day the plan is finished and the 26th (23:59) of every month, you can continue using it. The SIM is automatically terminated on 27th of every month if you do not recharge the SIM by 26th. *If you would like to recharge at convenience store, you need to apply the recharge by 26th and the payment need to be done by 27th (23:59) at convenience store.
Q. Can I terminate the SIM? (Is any procedure needed?)
A. It is prepaid SIM, so therefore the SIM is automatically terminated without recharge after the charge expiration date.
If you have any questions, Please inquire from the form below.

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COMST Support Center

Business hours: 10:00-18:00 JST weekdays