The phone is displayed under the phones tab as it sends a multicast message to the IP that the PBX is listening to but since this is not a supported device you cannot assign it to an extension.
Only supported devices can be auto assigned to extensions as the PBX includes a template for those devices with the correct settings. Please find a list with our supported devices here:
https://www.3cx.com/sip-phones/
How do I set manually? What do you mean when you say "connecting to the phone admin directly"??When not supported phones, it doesn't mean it will not work with 3CX but at least you can't use auto provisionning to send configuration to the phone, BTW you can just try to set it manually connecting to the phone admin directly , if it's impossible to use , you'll need to buy a supported phone.
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