My customer has UCM 7.1 with Unity Connection 7.x. They have Mitel SIP based phones (model 5330 & 5320) which they want to use with UCM. I'm not sure how this will work. I think I need to add 3rd Party SIP Phone (Basic) in UCM but not sure what else is involved (like maunal configuration on Mitel phones etc.). Please let me know if anyone has any experience in this, I really appreciate the help.
You will most likely need to add them as 3rd party SIP phones, but Mitel should be able to tell you that they've tested and confirmed how exactly to set these phones up with your specific version of CUCM. This being said if the phones won't register to the CUCM server you'll need to take detailed CCM service traces with SIP stack trace enabled in order to determine why exactly the registration is failing. Again, make sure you have Mitel on the phone whenever you try to get the phones up and running because they will know their product best and I've had 50+ customers get their 3rd party SIP phone configuration setup solved by their 3rd party vendor because of bad configuration on the phone.