The InmateAid discount phone service replaces the high per-minute rate with a flat rate of $0.21 per minute. There is no separate connection fee under that structure. Your inmate still places the call through Securus using the InmateAid forwarding number, and the funds still come from his Securus account, but the rate he is charged is dramatically lower.
Here is what the math looks like on a 15-minute call at your current rate: $1.85 connection plus $0.88 per minute for 15 minutes comes to $15.05. The same call through the InmateAid number runs $3.15. That is a savings of $11.90 per call. Put another way, his call money goes roughly five times further using the InmateAid number than it does at the current Securus rate.
The money still flows through Securus and comes out of his account. What InmateAid does is provide a forwarding number that triggers Securus's lower rate tier rather than the expensive local or standard rate you are currently being charged.