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Mobile Broadband Implementation Guidelines for USB Devices

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This topic provides specific implementation guidance to help mobile broadband device manufacturers produce compliant USB devices for Windows. It should be used in conjunction with the USB NCM Mobile Broadband Interface Model (MBIM) V1.0 specification released by the USB-IF Device Working Group.

The information in this topic applies to:

  • Windows 8
  • Windows 8.1

Delaying MBIM Open

MBIM devices may require time to complete initialization when they receive MBIM OPEN message from the host. The device should wait for its initialization to complete before responding to the MBIM OPEN message. The device should not respond to the message with error status like MBIM_STATUS_BUSY and expect the host to poll the device with MBIM OPEN messages. Responding to MBIM OPEN with a status other than MBIM_STATUS_SUCCESS terminates the initialization process on the host.

Multi-carrier\Multi-subscription

Please refer to IHV Guidance for Implementing Multimode- and Multicarrier- Capable MB Devices for details.

MBIM_CID_HOME_PROVIDER

MBIM devices must not fail a SET MBIM_CID_HOME_PROVIDER request with the following listed status codes under the mentioned circumstances. The following statuses are valid for the QUERY MBIM_CID_HOME_PROVIDER request but are not applicable for a SET request.

  • MBIM_STATUS_SIM_NOT_INSERTED - MBIM devices must not fail a SET MBIM_CID_HOME_PROVIDER request with status as MBIM_STATUS_SIM_NOT_INSERTED if the SIM for the new home provider is present but the SIM for the old home provider is not inserted.
  • MBIM_STATUS_BAD_SIM - MBIM devices must not fail SET MBIM_CID_HOME_PROVIDER request with MBIM_STATUS_BAD_SIM if the SIM for the new home provider is good but the SIM for the old home provider is not bad.
  • MBIM_STATUS_PIN_REQUIRED - MBIM devices must not fail SET MBIM_CID_HOME_PROVIDER request with MBIM_STATUS_PIN_REQUIRED regardless of whether the old or new SIM is pin locked.

MBIM_CID_VISIBLE_PROVIDERS

  • MBIM_STATUS_SIM_NOT_INSERTED - When MBIM_VISIBLE_PROVIDERS_ACTION is set to MBIMVisibleProvidersActionRestrictedScan the MBIM device must not fail MBIM_CID_VISIBLE_PROVIDERS request with MBIM_STATUS_SIM_NOT_INSERTED because the SIM for the current home provider is not present.
  • MBIM_STATUS_PIN_REQUIRED - When MBIM_VISIBLE_PROVIDERS_ACTION is set to MBIMVisibleProvidersActionRestrictedScan the MBIM device must not fail MBIM_CID_VISIBLE_PROVIDERS request with MBIM_STATUS_PIN_REQUIRED because the SIM for the current home provider is PIN locked.

Responding to Pin Operations

MBIM devices must follow these guidelines when responding to MBIMPinOperationEnter requests:

  • For successful MBIMPinOperationEnter requests, when the device no longer requires a PIN, the device must set status to MBIM_STATUS_SUCCESS and MBIM_PIN_INFO::Pin Type to MBIMPinTypeNone.

  • The device must set status to MBIM_STATUS_SUCCESS for PIN-enable and PIN-disable operations when the PIN is already in the requested state. The device must set MBIM_PIN_INFO::PinType to MBIMPinTypeNone. Other members are ignored.

  • When a PIN mode is changed from Disabled to Enabled, the PIN state should be MBIMPinStateUnlocked.

  • If PIN1 is enabled, the PIN state becomes MBIMPinStateLocked when the device is power cycled.

  • For all other PINs, the PIN state can change from MBIMPinStateUnlocked to MBIMPinStateLocked depending on mobile broadband device specific conditions.

  • PIN Not Supported: If a PIN operation is not supported by the device, the device must set status to MBIM_STATUS_NO_DEVICE_SUPPORT. For example, enabling and disabling PIN2 is not typically supported by mobile broadband devices so the above error code must be returned. All other members are ignored.

  • PIN Must be Entered: If a PIN operation requires a PIN to be entered, the device must set status to MBIM_STATUS_PIN_REQUIRED and MBIM_PIN_INFO::PinType to MBIMPinTypeXxx. Other members are ignored.

  • PIN Change Operation: If the device restricts the change of PIN value only when it is in enabled state, a request to change in disabled state must be returned with MBIM_STATUS_PIN_DISABLED.

  • PIN Retrial: On failure, the device must set status to MBIM_STATUS_FAILURE, and MBIM_PIN_INFO::PinType to the same value as specified in MBIM_SET_PIN. Other members are ignored except for MBIM_PIN_INFO::RemainingAttempts. This may occur when an incorrect PIN is entered.

  • PIN Blocking: The PIN is blocked when the number of MBIM_PIN_INFO::RemainingAttempts is zero. If the PIN unblock operation is not available, the device must set status to MBIM_STATUS_FAILURE and MBIM_PIN_INFO::PinType to MBIMPinTypeNone. MBIM_PIN_INFO::RemainingAttempts should be set to 0 and all the other members are ignored. Note  If the device supports PIN unblock operations, the device should follow the PIN Unblocking step to respond to the request.

  • Unblocking PIN: The PIN is blocked when MBIM_PIN_INFO::RemainingAttempts is zero. To unblock the PIN, the device may request a corresponding PUK, if applicable. In this case, the device must set status to MBIM_STATUS_FAILURE, MBIM_PIN_INFO::PinType to the corresponding MBIMPinTypeXxxPUK, PinState to MBIMPinStateLocked, and MBIM_PIN_INFO::RemainingAttempts should have the number of attempts allowed to enter a valid PUK.

  • If PIN blocking results in the device or SIM becomes blocked, the device must send a MBIM_CID_SUBSCRIBER_READY_STATUS notification with ReadyState set to MBIMSubscriberReadyStateDeviceLocked.

  • If there is an active PDP context at the time of PIN1 blocking, the device must deactivate the PDP context and send notifications to the operating system about the PDP deactivation and link state change.

  • For successful requests, the device must set status to MBIM_STATUS_SUCCESS. Other members are ignored.

  • For failed MBIMPinOperationEnter requests, the device must set status to MBIM_STATUS_FAILURE and include applicable data as per the following details:

    • PIN Disabled or PIN Not Expected: For MBIMPinOperationEnter set requests, when the corresponding PIN is either disabled or currently not expected by the device, the device must set MBIM_PIN_INFO::PinType to MBIMPinTypeNone. All other members are ignored.

    • PIN Not Supported: If the given PIN is not supported by the device, the device must set status to MBIM_STATUS_NO_DEVICE_SUPPORT.

    • PIN Retrial: In this mode, the device requires the PIN to be re-entered as the MBIM_PIN_INFO::RemainingAttempts value is still non-zero for this particular type of PIN. The device must set MBIM_PIN_INFO::PinType to the same value as that of MBIM_PIN_INFO::PinType in MBIM_SET_PIN.

    • PIN Blocking: The PIN is blocked when MBIM_PIN_INFO::RemainingAttempts is zero. If the PIN unblock operation is not available, the device must set status to MBIM_STATUS_FAILURE and MBIM_PIN_INFO::PinType to MBIMPinTypeNone. All the other members are ignored. Note  If the device supports PIN unblock operations, the device should follow the PIN Unblocking step to respond to the request.

    • PIN Unblocking: The PIN is blocked when MBIM_PIN_INFO::RemainingAttempts is zero. To unblock the PIN, the device may request a corresponding PIN Unlock Key (PUK), if applicable. In this case, the device must set MBIM_PIN_INFO::PinType to the corresponding MBIMPinTypeXxxPUK with the relevant details.

    • Blocked PUK: If the number of failed trials exceeds the preset value for entering the MBIMPinTypeXxxPUK, then the PUK becomes blocked. The device must signal this by setting status to MBIM_STATUS_FAILURE and MBIM_PIN_INFO::PinType to MBIMPinTypeNone. In case PUK1 is blocked, the device must send a MBIM_CID_SUBSCRIBER_READY_STATUS with ReadyState set to MBIMSubscriberReadyStateBadSim.

    • MBIM devices must follow these guidelines when responding to MBIMPinOperationEnable, MBIMPinOperationDisable, or MBIMPinOperationChange requests.

Auto Packet Service Attach

MBIM devices that support Auto Packet Service Attach manage the attachment and detachment of packet service from the mobile network at their discretion. The host may still send an attach request to such a device on user request. When the device receives the attach request from the host it should handle as follows:

  • If the device is not attached and not in the middle of an attach operation and is capable of attaching then it should initiate a new attach procedure with the mobile network.
  • If the device is not attached but in the middle of an auto attach operation then it should wait for the auto attach operation to complete and complete the attach request from the host with the status of the auto attach operation.
  • If the device is already attached then it should complete the attach request from the host successfully.

Signal Strength Loss and Data Connection Loss

When a device loses signal strength the device must indicate MBIMActivationStateDeactivated followed by MBIMPacketServiceStateDetached followed by MBIMRegisterStateDeregistered in that order. If the device loses packet service while it is context activated the device must indicate MBIMActivationStateDeactivated followed by MBIMPacketServiceStateDetached in that order. The following sequence diagram shows the interaction between the host and the device.

Sequence diagram illustrating the interaction between the host and the device.

DNS Server Information

When Basic IP information (as defined in MBIM section 10.5.20.1) is provided via MBIM_CID_IP_CONFIGURATION, DNS server information (as defined in MBIM section 10.5.20.1) can also be provided via MBIM_CID_IP_CONFIGURATION. When DNS server information is updated, MBIM_CID_IP_CONFIGURAITON must have the complete Basic IP information obtained before. DNS server information can be provided solely via MBIM_CID_IP_CONFIGURATION even if the Basic IP information is not provided via MBIM_CID_IP_CONFIGURATION. This applies to both IPv4 and IPv6.

IPv6

For basic IP information (as defined in MBIM section 10.5.20.1), the expected IP Layer configuration mechanism is from router advertisement (RA). For DNS server information (as defined in MBIM section 10.5.20.1), the expected IP Layer configuration mechanism is DHCPv6.

  • Basic IP information from RA - If a mobile network provides Basic IP information (as defined in MBIM section 10.5.20.1) via RA, then MBIM devices must allow RA packets to be forwarded to the host and must not intercept the RA packets or provide the Basic IP information present in the RA packets via MBIM_CID_IP_CONFIGURATION.
  • DNS server information from RA - The only IP Layer configuration mechanism for DNS server information (as defined in MBIM section 10.5.20.1) supported by Windows is DHCPv6. MBIM devices must configure DNS server information, even if present in RA, via MBIM_CID_IP_CONFIGURATION.
  • Basic IP information and DNS server information from DHCPv6 - If a mobile network provides basic IP information and DNS server information (as defined in MBIM section 10.5.20.1) from DHCPv6, then MBIM devices must allow DHCPv6 packets to be forwarded to the host and must not intercept the DHCPv6 packets or provide the basic IP information and DNS server information present in the DHCPv6 packets via MBIM_CID_IP_CONFIGURATION.

MBIM_CID_RADIO_STATE

MBIM devices must not fail MBIM_CID_RADIO_STATE operations with status of MBIM_STATUS_SIM_NOT_INSERTED when SIM is not present. Radio operations must not be failed due to SIM absence.

Byte-Ordering Requirements for Authentication CIDs

Data in the byte array fields listed below must be in host-byte order.

MBIM_CID_SIM_AUTH

MBIM_SIM_AUTH_REQ

  1. Rand1
  2. Rand2
  3. Rand3

MBIM_CID_AKA_AUTH

MBIM_AKA_AUTH_REQ

  1. Rand
  2. Autn

MBIM_AKA_AUTH_INFO

  1. Res
  2. IK
  3. CK
  4. Auts

MBIM_CID_AKAP_AUTH

MBIM_AKAP_AUTH_REQ

  1. Rand
  2. Autn

MBIM_AKAP_AUTH_INFO

  1. Res
  2. IK
  3. CK
  4. Auts

Windows supports configuring Link Maximum Transmission Unit (MTU) only during device initialization. Windows does not update the Link MTU based on the MTU reported using MBIM_CID_IP_CONFIGURATION. Devices must communicate the network supported link MTU using the MBIM_FUNCTIONAL_DESCRIPTOR.wMaxSegmentSize. Link MTU values reported in this manner should be at least 1280 and at most 1500.