我向Obihai Technology的专家询问了英台的问题，以下是他们的回答，希望对大家有帮助。
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The 5212 and 5224 IP Phones support the Mitel Call Control (MiNet) protocol and Session Initiated Protocol (SIP).
OBiPLUS can support SIP IP phones, but only for basic registration and calling. It is likely that some of the business features available with the phone, would not work unless you are using the MiNET protocol with an associated service/IP-PBX.
There is an OBiPLUS admin guide here: http://www.obihai.com/docs-downloads.html
The discussion form for OBiPLUS is here: http://www.obitalk.com/forum/index.php?board=17.0
Using a SIP phone with an OBi202 (as a Google Voice gateway) is here: http://blog.obihai.com/2012/08/use-your-obi202-as-google-voice-gateway.html
OBiPLUS / Obihai tech support will not be able to assist you in getting the MiTel phone working with OBiPLUS.
Thank you,
Obihai Technology