That's exactly what Voxalot lets you do. Register an account and add all your providers to it. Select SIP register = yes on any accounts that you want incoming calls. Then register your phone/softphone to Voxalot and no other providers. You will also get a single voicemail system through Voxalot so you can turn off voicemail for each individual provider. To make outgoing calls with Voxalot you then need to add some dial plans and select the account to route calls to. You'll never look back!
