How Can I Be A Sys-Admin On The Road?

Peter Cooper asks: "I'm a server administrator who also has to visit clients, meaning I'm often out of the office. As a 'one man outfit', this means my servers are at risk during this time. I was planning to get a cellphone that can receive e-mail, and a PDA which can connect through the cellphone, so that I can SSH from anywhere in the country, but the amount of phones, PDAs, and connectivity options, are very confusing. Do other admins have recommendations for phones, PDAs, or other systems so I can be an admin on the road? I'm in the UK, but suggestions for elsewhere are also welcomed, as others may find them useful."