Number 070 9287 3259 is potentially valid
Ofcom records show that numbers starting 070928 are allocated to Vodafone Ltd (C&W). Note that due to number portability if an individual number has moved to a different operator this information is not publicly available.
Ofcom's last recorded change for this number range was May 2001.
The correct way to write the telephone number 07092873259 is 070 9287 3259
For more information on tariffs and usage of numbers starting 07 please visit the page on 07 numbers