We used CallSears for a week. It made bad battery life worse on the devices (which most have to be rotated since the batteries are permanently declining) and caused ShopSears or the SNC app to misbehave. When we did use the app it never worked. In fact it inadvertently hung up and crashed a few times.
No sense in Pebbling it to #ithelp because you'll just get a generic "please kindly describe the problem" response to a post already describing the problem in full detail. Twenty minutes later they close the ticket when nothing was resolved. Happens every time, so our store (and many others) have to live with IT issues or fix them ourselves if we are able.
It seemed to be a colossal waste of money to develop a phone system interface app for 5-year old devices past their useful lifecycle, just like it was to develop an app (ShopSears) to interface with a 20-year old register.
We were and are doing just fine with telephones attached to a wall and placed at every cashwrap. Our store has over 50 of them in the building. If this is to improve call answer rates, that's silly. Walk over to a blasted phone and answer the call.