The Notts County Ladies striker has been selected in manager Mark Sampson's squad for the matches against Norway and Sweden in Spain in late January.
Leicester-born Williams, 28, was last called up in April 2013 and was "shocked" by her international return.
"I never retired from England and never gave up on the idea of playing again," she told BBC Radio Leicester.
"But it got to a point after three years where I thought, 'I've had my time'.
"At first I thought someone was having me on."
Williams' club team-mates Carly Telford, Jo Potter, Jade Moore and Ellen White have also been chosen.
It was England Lionesses regular Bassett who alerted Williams to the good news about being part of the 28-player squad for the games against Norway at La Manga Club on Sunday, 22 January, and Sweden at the Pinatar Arena on Tuesday, 24 January.
Williams said: "She texted me to say 'you really need to check your emails'.
"She's like my fairy godmother; she watches over me. She's brilliant."
The last of 13 caps Williams won came under Hope Powell in 2013, and she is thrilled to be involved under Sampson for the first time, with the chance to prove she is worth keeping in the squad for Euro 2017 in the Netherlands.
"I will be like a kid in a sweet shop," the former Leicester, Birmingham and Chelsea forward said. "It's doing something I love doing every day. I can't wait to get out there.
"For me, it is going out there and showing him what I have got. Hopefully I can impress and get called up to the next camp."
On 10 January, Williams signed an extended contract with Notts, having been with the Women's Super League One club since 2015.
Rachel Williams thought news of her recall to the England squad after a near four-year absence was a wind-up.