To be honest, I do it rather simply:
I have this in my import:
import org.apache.commons.lang.RandomStringUtils as RandomStringUtils
Then, I use this
WebUI.setText(findTestObject('{TestObject}'), RandomStringUtils.randomNumeric(10))
so you could append “070” to the front WebUI.setText(findTestObject('{TestObject}'), ("070") + RandomStringUtills.randomNumeric(7))
That’s what I use for a phone number. I also use this to randomize email addresses by appending RandomStringUtils.randomNumeric(3)
to the email address.