For a number that's a magnitude (as opposed to a mere sequence of digits like a phone number), you cannot omit words like "hundred" and "thousand". The normal way to say 1417 is "mille quatre cent dix-sept". Numbers between 1100 and 1999 are sometimes pronounced with a 2:2 grouping, but with cent after the first group: "quatorze cent dix-sept". This is mostly done for years, although it will be understood if you do it for some other number, but even for years it's more common to use mille. This does not carry over after 2000: 2017 is "deux mille dix-sept" only.
If you say "quatorze dix-sept", it just sounds like two separate numbers. If the listener expects a single number, he might interpret the digits as the number you intended or get confused because he's heard two numbers when he was expecting one. This has a higher chance of working when the listener is just writing the digits down, but it's never a standard phrasing.
It's different when you say sequences of digits that aren't a magnitude, such as phone numbers, bank account numbers, social security numbers, etc. In English, these are still "numbers", but in French we have a different words: they are numéros, as opposed to nombres. For a numéro, it's normal to group digits, typically by two or three. For French phone numbers, always group by two (except for numbers selected to be memorable with a different grouping, e.g. 0922333444 would probably be "zéro neuf vingt-deux trois cent trente-trois quatre cent quarante-quatre" or "zéro neuf, deux deux, trois trois trois, quatre quatre quatre"). When a numéro is written out with space or dashes between groups, it's typical to read each group as a number. For example a French social security number like 1 22 33 44 555 666 77 is usually pronounced "un vingt-deux trente-trois quarante-quatre cinq cent cinquante-cinq six cent soixante-six soixante dix-sept".
For digits after a decimal point, if there are two or three digits, pronounce them as a number: 3.14 is "trois virgule quatorze". For more digits, there's no firm rule. It's common to group by three, but grouping by two is also possible, as is saying each digit separately, and even varying the grouping size based on what feels easier to parse or pronounce.
My answer applies to France. Other variants of French may be different.