It could be even simpler than a need for a business card-- a tiny bit of a quality contact cleaner on the phone's contacts and the battery contacts might be enough and wouldn't hurt anything. (Just use it very sparingly.)
I use the products from Caig Labs-- for this I'd try DeoxIt. One small container lasts most people for many years. I swear by the stuff, and no I don't sell it of work for the people; I spent years in recording studios where nothing can have a marginal connection or you'll end up with a Rice Krispies commercial from all the "snap, crackle & pop"...
Basically, no connection is no connection but a light touch and some oxidation can sometimes imitate no connection... One drop on a q-tip and a light wipe and you're all set. If that's not enough, move on to layers of tape, thin card stock (as in a business card), etc. It is also fantastic for kids toys (on the inside only mind you) as contacts get poor.
For DeoIt, you can buy it direct from Caig if you like at: DeoxITÂ®