Having call forward external issues on 3 systems CIX40 and CIX100 all with 5.2 software and multiple models of handsets.

The issue: it just won't call forward external on all DP stations. COS has Tandem trunks checked.

A lot of employees are trying to have their stations ring their cell phone for work-at-home scenarios.

Losing my mind because it seems so simple but has not worked well at all.

All stations have a system call forward to voicemail activated. When call forward to external number is entered, caller hears it ring and then it goes back to transfer station or V/M - wherever it was transferred from.

any ideas on what I may have missed?