sforce not defined in test environment, but defined in sandbox

Hi to all, I have an aura component, i developed it in sandbox, and it fully works, if passed to the test environment when I try to open it i've got the following error:
sforce is not defined

The function that is responsible is this:

editPanel: function(cmp, evt, helper) {
        var params = evt.getParams();
        if (params.label) {
            sforce.opencti.setSoftphonePanelLabel({
                label: params.label
            });
        }
    },

in the sforce.opencti part,
I tried to import connection.js and apex.js, but still no luck, can anyone help me to find out why this happens?
Thanks in advance, Antonio.