Sounds like you guys have capped plans... not so lucky here.
We moved and it took about 6 weeks to get a phone line installed, so in the meantime we had to use our mobiles (cells). Because we had just moved into a brand new home I had a heap of companies to call to sort out fencing, blinds, etc. Even though I'm on a business plan with 'reasonable' daytime rates it added about $AUD400 ($USD312) to our next bill.
Mobile calls are a ripoff here. Kids are going into debt before they've even finished school.