I am planning on purchasing 4 SPA504G IP phones but want to confirm that they will share a single DID. All phones will be registered directly with my VOIP provider. Can I set them up so that when a call comes in, all phones ring and one person can place a call on hold and have a different phone continue the call? I nknow there is a share extension function, but was not sure if it will work when the phones are connected directly to the VOIP provider. It also appears that ext_1 cannot be set as shared. Any help would be appreciated.