The problem of not having a connection to send coins is a non issue..
You make it available, and use a web based coin payment page..
If you look at captive portal and hot spot, they all work perfectly fine..
It's not quite that simple; typical captive portals require that you trust them with your credit card number, but you would never want to give a captive portal your private key.
yep, with bitcoin every party is his own payment processor so the clients need bitcoin network connectivity or bad things may happen. Imagine a client having a shared wallet with another member of his family tries to pay you an hour of internet connectivity but the other person spent some coins on a new pair of shoes the shop next door.
His mobile wallet doesn't know it when creating the transaction so it will look like a double spend to you, but if you share that info with him, the wallet could redo the transaction using the correct coins. Now he happily browses the web searching to buy geeky things that cost the same amount as spent by the other family member
