| With the 51C (same for 61C and 81C), your A06 key can actually conference up to 30 parties although voice quality declines significantly as you go up in parties. Option 11C is limited to 6 parties due to a difference conference circuitry used. That being said, you are likely to run into voice quality issues with 11 external parties due to noise on those circuits. Go ahead and try it.
Beyond this solution, you could look at something like the Meridian Integrated Conference Bridge. |