Administrative Review for Tier5

[samidare]

Hi.
I got refusal letter after I submitted my biometric certificate for Tier 5. It took one month.
the letter says, I can request for the administrative review if I'm not convinced this decision so I'm working on it.

Right now I am filling out my information on Page 1 of review form (https://www.gov.uk/government/uploads/s ... equest.pdf),

and it seems like I need to write my phone number of a landline but I don't have one at my place.
In the instruction of this form
(https://www.gov.uk/government/uploads/s ... -guide.pdf),

'You must include the full number including the city, area and country codes. This is NOT your mobile/cellular phone'.

Does this mean could be saying 'You must have a landline phone number'?
For me, It looks like only saying about how to write down your phone number.. If you don't have one, Can we skip this part on the form?

This is a really small thing but for UK immigration they can not take any joke. So I would appreciate if you could help me with this question.
Thank you,