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Troubleshooting: SPA Phones Contacting Unknown/Foreign IP Addresses

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If you deploy DHCP OPTION 150 to direct your phone to a provisioning server, be sure to convert the provisioning server's IP address to hex.

If you insert a text-string when configuring your DHCP server, the SPA phone will automatically convert the string from hex, even though it is a text string. The hex-converted string can result in your phone attempting to access foreign IP addresses.

Following is an example where the network admin noticed traffic from phones to foreign IP addresses that were not related to the business.

cap-0030.jpg

cap-0031.jpg

Note how instead of using a hex-encoded IP address, the DHCP server was configured to offer OPTION 150 as a text string of "<http://myprov-server...> which resulted in phones reaching out to 104.116.116.112 and 58.47.47.112 which is *not* what the administrator intended.

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