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Troubleshooting and Replacing a Faulty MC

There are some circumstances where an MC Phone will fail to function. In some circumstances, the device has undergone hardware failure and will need to be replaced. However, many symptoms that appear to reflect a failure can be explained and resolved by troubleshooting. This article outlines common symptoms and troubleshooting steps that can be followed to determine if the phone has failed and requires replacement.


When determining if a unit is faulty, the following checks must be made. As per the device's replacement warranty, Cisco Meraki can replace a faulty device. However, in order to satisfy all stakeholders and minimize both downtime and cost, troubleshooting must be done to determine if an RMA is the correct path to follow.
The following symptoms and steps will help determine if an MC unit has failed:

If the MC is unable to make to make calls (or calls have one-way audio)

  • Is the MC able to establish a successful SIP flow with the call provider? 
    • The MC must reach out to a SIP provider to make an external call. A detailed look into the SIP call flow can be found hereIf an upstream firewall is preventing the unit from establishing or maintaining its calls, they will either fail to connect or result in one-way audio.

    • For assistance on determining the root cause of these issues, troubleshooting further upstream would be recommended to isolate where traffic is being lost and does not necessarily indicate hardware failure of the MC unit.

    • Please contact support or reference our documentation if assistance is required in isolating these types of issues.

If the MC screen is completely off

  • Is PoE power being supplied to the correct port on the MC phone?
    • The MC has two Ethernet interfaces, a network interface (Indicated by a LAN icon) and a passthrough port (Indicated by a PC icon)PoE power must be supplied through the Network Port to function.
    • If using an AC adapter, ensure that the AC adapter is functional and fully inserted into the back of the MC phone.
  • Is full 802.3af power available to the unit if powered via PoE?
    • The MC74 requires 802.3af power if being supplied via PoE. This means the MC will request up to 15.4W of power via LLDP which will need to be available for the phone to power on. If this is not available, the MC will fail to boot.
  • If using a PoE injector, replace cabling between the MC and “out” jack on the PoE injector, and the cable from the “in” jack on the PoE injector to the LAN. Ensure all Ethernet cabling is less than 100 meters in length.

If the above fails to resolve the issue, this unit is faulty and needs an RMA.

If the MC powers on but shows "No Internet Connection"

  • Verify Physical/Layer 1 Connectivity
    • Replace the network cable. A bad cable may cause the device to receive power but no data connection.

    • If using a PoE switch, try connecting the MC to a different switchport.

    • If using a PoE injector, use another known-good phone or other PoE device to test the PoE injector.

  • Does the phone have a valid WAN connection?
    • Check the upstream network configuration.
    • Ensure that the MC is on the appropriate VLAN.
    • Verify that the upstream switchport is configured to allow the MC on the network.
    • Check that the MC is getting a valid IP configuration via DHCP (Static IPs are not supported at this time).
    • Ensure that any firewalls upstream are allowing the MC to communicate with Dashboard (required ports are listed in Dashboard under Help > Firewall Info)

If the above fails to resolve the issue, this unit is faulty and needs an RMA.

If the MC is frozen at the Cisco-Meraki logo

Depending on when the MC freezes in the boot process, this symptom may point to a faulty unit and require an RMA. The MC boot process occurs in three steps:

  1. A black background with a white Cisco-Meraki logo in which hardware initialization takes place.
  2. A white background with a green Cisco-Meraki logo in which the LED on the upper right hand of the unit will flash and software initialization takes place.
  3. The MC screen will show initializing, in which the phone dialer loads and the MC is ready for use.

Take note of where in the process the MC freezes, then contact support to discuss next steps.

Replacing Faulty Devices (RMA)

If the steps outlined above have been followed and indicate that the unit requires an RMA, please contact support to begin the RMA process. Please be prepared to outline the troubleshooting steps that have been taken so far, to help expedite the process.

Note: Support may recommend additional troubleshooting steps not outlined in this article, depending on the nature of the specific issue.

Please also reference our RMA documentation article for additional information about device replacement.

After the replaced phone is received, claim the device using the Serial Number and add it to the network. Make sure to assign the new phone any required Tags as well as the contact from the replaced phone

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