Have you looked at SIP Gateway?
https://video2.skills-academy.com/en-us/microsoftteams/sip-gateway-plan
"SIP Gateway lets your organization use any compatible SIP device with Microsoft Teams to preserve your investments in SIP devices. Now you can sign-in to Teams with your corporate credentials and make and receive calls with a compatible SIP device. Compatible devices can be Skype for Business IP phones with standard SIP firmware, Cisco IP phones with multiplatform SIP firmware, or SIP devices from vendors such as Poly, Yealink, and AudioCodes. To find out how to configure your SIP devices for SIP Gateway, see Configure SIP Gateway."
Check if your devices are compatible on the link provided above.
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