Number 070 3191 9138 is potentially valid
Ofcom records show that numbers starting 070319 are allocated to Magrathea Telecommunications Limited. 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 March 2002.
The correct way to write the telephone number 07031919138 is 070 3191 9138
For more information on tariffs and usage of numbers starting 07 please visit the page on 07 numbers