No, you cannot use Soracom services without a registered payment method.
Soracom operates on a postpaid model. Consequently, a valid credit card is required to activate Soracom IoT SIM cards or utilize additional services.
Although some Soracom products include a coupon credit to offset initial fees, a credit card must still be registered to the account before you can begin using the service.
For assistance with adding a payment method, please refer to the Payment Settings documentation.
For detailed information regarding usage costs, please refer to the Pricing and Fee Schedule.