Hi and welcome to the forum
I've just been through this again, our business contract expires in 3 weeks so I have been looking to get the new contract in place.
To give you a better reply it would help to understand more about your phone use, but I can tell you what I found over the last 4 weeks for our business.
We have 17 handsets, 4 of which are blackberry's for the directors and sales guys. I spend a lot of time travelling round Europe, and my MD and myself also visit Japan frequently, so this overseas use had to be taken into account.
When analysing our statements for the last year it would seem that by normal or typical use in the market we are quite low users of minutes. This may be because we have very strict controls over using company mobiles for personal use (a £10 per month per person limit).
Typically we use around 1700/1800 minutes per month, so I was looking for a 2000 minute per month package ideally.
We have been with T Mobile for the last two years, but netwrok coverage here in semi rural lancashire is terrible, we found the same in other rural areas also, so for this reason T Mobile was ruled out from the start.
O2 and Orange could not support effectively the ratio of handsets to a 2000 minute business plan, essentially, to get 17 handsets we would need to subscribe to a 4000 minute plan.
This left me really with 3G and Vodafone. As a business we don't really have any need for 3G, and the actual 3G coverage is also patchy in rural areas. SO in the end I selected Vodafone, they are able to provide the right package in terms of minutes, a 2000 minutes per month plan, and also have a "vodafone passport" which will significantly reduce the cost of calling from abroad for our business.
In terms of email, I find the blackberry to be great. There are different levels of Blackberry server software, but the Enterprise and Professional versions give 100% sync with outlook which we use heavily.
I did look at a couple of windows mobile solutions (including IPhone), but after seeing 5 different companies and looking at the changes we would have toi make to our Exchange server decided not to go down that path. The general opinion from the comms companies is that Blackberry are the experts in the area of mobile comms, Windows mobile still seems to have quite a lot of issues.
Some of the Blackberry's have 3G, but for either a windows or blackberry solution I think you need an MS Exchange server running. We use exchange 2003, but I understand that 2007 is also fine to use.
I would recomend going to 2 or 3 comms companies, it is a fierce market at the moment and I found them trying to cut each others throats for our business. They can also do the legwork for you in terms of finding the most suitable package.