The Plantronics CT12 and CT11 will interfere with a Wireless Network since they both use a 2.4Ghz frequency.
If they already have the CT12/CT11 and a wireless network then move the CT12/CT11 as far away to the router or wireless cards as possible or contact the wireless provider to see if they can change the frequency of the Router itself.
Note: The CT11 and CT12 have been discontinued.
Recommend PTR CT14 or AT&T Marathon Partner bundle.
