I have seen a lot of post on here about Cisco phones, and I would like to give my advise.
I would recommend buying Cisco’s SPA series of phones as they are SIP enabled,
If have some other Cisco phone/s like Cisco’s CP series, then there is a way to get them to work but It maybe a little bit complex, ()
Personally I would not recommend using Cisco phones on FreePBX, Instead use a Phone by Yealink or Sangoma,
I think you are giving not very wel informed advice.
I own both types of Cisco Phones. (CP-8841 and the SPA504g)
There is no doubt that the SPA phones are robust, reliable and well configurable with FreePBX,
they are also EOL (End-Of-Live) meaning no security updates and no factory supported repair options.
The texts you’ve been reading (Pobably some of mine) are about the CP-88xx series running the Cisco Enterprise Firmware. Those are harder to setup.
The identical phones can also come with 3PCC firmware. The latter is fully compatibel with FreePBX is and has nearly identical setup as the SPA series via it’s webinterface.
I currently run 4 CP-8841 they have participated in >2500 call’s. They work stable and full features. Only downside, is any changes done to them is done server-side in a XML file.
But that is a choice they can be converted any time.
I installed them, but also use them every day, the largers screenspace is a treat.
Ow and they look great on the desk