We have TalkTalk as our home phone provider in the UK to call my family. We pay under £20 / month for home phone and internet. It is a VOIP provider, but for the most part the phone calls are no better or worse than my family calling me. In my plan it includes "unlimited" calls to the states as long as the calls are no longer than 60 minutes.
If he already has BT or Sky as his home phone provider he may want to consider getting the "International Freedom" Plan added to his current plan, which includes "unlimited" 60 minute calls to the US for an additional £5 per month. Much cheaper than buying phone cards if you're making regular calls.
I have a Flext contract with T-Mobile (UK) - they've recently changed Flext plans to be able to use your credit bank to call and text internationally (yes, including the USA) without incruing excess charges! However, I must say that T-Mobile UK is pants for media messages (pictures) to US networks - they just don't work as it's not reciprocated, so I just send text to their email addresses with pictures in them.
I know O2 have a "My Country" Tarrif for Pay & Go customers that includes x amount of free minutes to call the states from your mobile each month as long as you top-up the minimum amount...
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My grandmother has WoW (Wide Open West) in the US for her cable and home phone... My brother got her set up on there for something like £99 a month and it's supposed to include an international call package as she calls her family in Germany (and used to call my grandfather's family in Italy) frequently.
We have a T-Mobile (US) Sim card that we use whenever we visit the states, however I was informed by T-Mobile US that they have a fatal error with connecting to Vodafone (which is my husband's provider), so the whole time we were in the states last I was unable to text him, but I could call him (however he still had to pay his extortionate rates for being abroad).
Hopefully someone else will be able to help you out with texting or calling from a US mobile, but I know all my family are on Verizon Wireless and get charged to receive (20 cents) and send (25 cents) International Texts, as Verizon will not include them in a bundle and International calls are extortionate as well...
Good luck sorting it all out!