I'm not convinced, but I think it may mean 'make a payment by means of a debit to your phone account'. This is often done to a mobile (cell) phone's account, but can also be done to a fixed line.
This is a case where language has to be adapted to respond to a new sort of technology. In my book, you can't 'pay' or 'pay in' value, but if that's the way a phone company chooses to express it, I'd better learn pretty fast. ;-)
Thank you. Please clarify whether "down the telephone line" has the meaning of payment through the line or whether "down" is the part of the verb phrase of "to pay-in value down" meaning yto pay in cash. Many thanks
It's a clumsy phrase. There's no reason for the hyphen in the verb- we normally use hyphens for phrasal verbs used as nouns. 'Down' refers to the telephone line I think, but it is not a natural sentence for me.