Travel Tools - Why ITA find me fares 365 days in advance but Airline says they cannot book it?

I looked for the answer and didn't found it.

Found on ITA a flight i want to do next year end of June, returning in July. ITA gives me the price and everything but when i call JJ they say i only can book 330 days in advance.

Anyone know how to avoid this, or why ITA validates the fares?

TIA

Don't know why ITA posts it but 330 days is common for booking. The routes don't even show up in the GDS systems until 330.

Funny, had an IST trip leaving January returning end of July, my TA could only hold the return at May 31. Would be interested to know the reason as well!