We've been using a VOIP hosted phone system for a couple of years. Although at the beginning it was OK, we find that a lot of calls get dropped mid-flow and the phones freeze for a couple of seconds. The telecoms service provider blames the DSL service and the DSL service provider says that they have no record of problems on their line. I'm pretty sure that it is not a contention issue as call quality is OK. Can anyone advise, please? Thanks.