I am currently 1 deep, mobile only.
This has worked quite well, but is vulnerable to a 9/11 type event and potentially to large scale power outages where mobile towers would be knocked out as well.
Biggest problems encountered during months where I have to get familiar with half the technical staff of a trading related organization - again! June has been terrible as I have has significant technical problems with my brokers, internet access, and charting service. Consequently I blew over my minutes by a mile and am not happy.
Any thoughts on a better combination without increasing my costs substantially as I think people spend a lot on their overall information systems packages already (Telecom, internet, financial data systems, etc.). I have not researched VoIP quality/reliability yet. I would prefer not to get a land line, but maybe I should - then I can stay on hold for all my technical staff friends... Also, my understanding is that a land line with an old school telephone that gets its power from the telephone line is probably the most effective safegaurd during emergency times such as a power outage.
So leaning to adding a land line and reducing the the number of minutes on my mobile plan at this time.