How to connect Cisco 8861 to SIP provider?

Question

VoIP

Please, I ask you not to kick too much, as everyone started somewhere.
There was a need for a SIP phone to connect it to 4 SIP accounts. Without much thought, I bought a Cisco 8861, but did not yet know what I would have to face. I assumed that everything is configured there through the phone itself (like the iPhone, for example) or the web interface. But now I understand that it, as it were, loads the configuration file from the TFTP server, and then I realized that nothing is clear at all.
Now it stands like a brick.
Question. If I need to connect it to SIP accounts, where should I start? How can all this be simplified? The maximum I can do is to put a TFTP server on an existing Synology. That is, putting CUCM (if I understand correctly) on a server or VM is already difficult due to the lack of equipment.
I don't need any super features - just connect it to SIP accounts.

Answer 1

Another client "I bought without thinking" :)
habrahabr.ru/post/121140
We read, delve into, configure, click "answer" :)))
You are only interested in tftp + xml config file, there will be 2: 1 default - 2nd mac .xml that is generated for the device, there are many links in the article, an example of the config can be taken in articles or assembled by yourself, the Internet will help