Often sales people and management will ask, "How do I check my voicemail from outside?" I always recommend that they enable voicemail to email, but for those that want it, you can set up a silent option in the IVR.
What I mean by silent option is that you will add another option to the IVR, but you will not announce that option in the recorded audio.
Add another entry and choose the Destination category of Feature Code Admin and then select Dial Voicemail <*98>
With VoIP.ms and PJSIP, you also need to go to the advanced tab and change the default expiration time from 3600 to 120.
I have not tested this with other providers yet as it would be disruptive to a client.
When I have time I will setup a backup provider and change my extension to use that normally and see how things go. The problem is that with a not very used system, it will still reregister every hour, so to catch it, I have to make a call between the fial time and the reregister time.
Additionally, your iPhone does not add a pause automatically. It adds a wait. A wait means you have to push a button to continue dialing. A pause will automatically continue dialing. Every single time I have updated a contact form email data it has added the wait and not a pause.
Mine is a pause, it's fully automatic when I've used it. It's only so often that it has come up, as I basically never call people, but when I've used it, it is 100% automated. I didn't even know the situation that you are running into could come up. Mine takes the number automatically and dials it, including the extension, automatically. At least it did in the past.
I've never even heard of this - of course it makes sense - using the pauses like JB mentions makes sense as long as the menu system doesn't change. :)
Bringing this full circle, the point is that you need a main DID for everyone to call into and get the operator, and then a second DID for everyone to call into and get the IVR directly so they can dial straight to the person.
No need for hundreds of DID.
If you have no operator, then your main number would just be the DID with the IVR.