There is no monthly bill for the phone instalments, just the invoice for the purchase price you should have received shortly after buying the phone. If your employer is also paying for your phone then you would need to submit that invoice. The fact that you are paying for this in monthly instalments should not make any difference. Alternatively: submit the direct debit entry from your bank statement if your employer wants proof of the amount you paid each month.

Hello @Adarshcpt, 

welcome to the o2 community and thank you for your contribution. 
I see that bs0 was already able to respond to your request. Thank you very much! 
If you still have questions about it then feel free to contact us again. 

Kind regards
Jessi