I have a Cisco SPA8000 configured to connect the voip system with 8 extensions. These 8 extensions are transformed into 8 analog lines by SPA8000. The 8 analog lines are connected to an old Mitel SX1000. From the analog phones connected to the Mitel, I can make external calls through Mitel -> SPA8000 -> SIP ... But in reverse direction, the Mitel is not able to pick up the calls of SPA8000.

I am not an expert of Mitel. My question is:

If SPA8000 has an incoming calls, does it need to dial a number (or do something to) to connect to Mitel first (for example, connect to the console and/or auto-attendent before putting the incoming call on Mitel)? Currently the SPA8000 does nothing. I tested using an analog phone connected to SPA8000, if there is a incoming call, the phone does ring, and I can pick it up. But if the SPA8000 is directly connected to Mitel. It seems obvious to me that the Mitel doesn't know there is an incoming call at all.

Your help is appreciated!