Unfortunately you won't be able to go back to a conventional landline and I think it is somewhat unlikely that VM would cover your losses in the event of a burglary. It would, however, be reasonable to expect your internet connection from VM should work reliably.
You need to find out what options are available from your alarm company to deal with the issue.
Alarm companies have been aware of this changeover for a long time but have not been proactive in helping customers with the change, based on topics on here. And, from the topics on here, they are certainly not holding back on trying to sell their customers new systems if they think they can.
You should investigate what sorts of connections are available for your alarm to work on a mobile signal. Your options may depend on the make/age of your existing alarm panel.
Some panels can take a communications card for mobile use. Some may be able to work with an add-on unit. There may be an option/device which monitors your landline connection and, if it fails, will automatically switch over to a mobile signal.
If you think your current alarm provider is not being that helpful or accommodating, seek some advice and quotes from other suppliers in your area to find out what your options are.
Worth noting, if you are speaking to other alarm companies, that you do not tell them you have a VOIP line with VM. The telephone socket on the back of the VM hub is designed to behave in a similar way to a conventional telephone wall socket. It is not a full VOIP connection/service. Talk of VOIP lines usually seems to prompt the alarm provider to tell you they can't connect the alarm and they need to sell you a new system!
