this is the correct snap build setup
parking is dynamic, while on a call you can just hit *** and it picks the first avail. lot - keys must be mapped for each lot, key cannot be dynamic
note we want to encourage the use of 701-703 - as setting up custom call parking lots is a good bit of work
This is how you would want the Call Parks set up on the account. First, you will need to ensure these are added or setup under Call Queues 
Extension 701 - Park 1
Extension 702 - Park 2
Extension 703 - Park 3
Note: It is very important to not change any of these especially the extension numbers, otherwise it will not work.
Once these are in place, you should then be able to Park calls to them.
How can you park calls?
-
While on a call, you can dial *** and it would dynamically park the call to any of these Call Parks.
- By using the Keys on your phones if they are setup. Please see below on how these are added on the phone's Snapbuilder.
Using these keys setup/added once you are in a call. You can press any of the Park keys and it will Park the call on that key.
How to retrieve a Parked Call?
1. Using the keys, as long as those keys are also setup on other phones, they will see that a call is Park on that key and they can simply click on that one and it will pick up that call.
2. Dial the Call Park extension like for example 701, 702, or 703 and it would pick up the Park call on that park extension.