No other way ?

[Rune Son of Bjarne]

This subject has been well debated on the downs. . .Many is of the belief that there must have been other ways and that Gandalf must have known at least one, but I don't think anything was ever concluded.

I personally think that there would have been other ways, but I doubt that they would have been alternatives. One could have spend ages searching for passes over the mountains and they would probably also have been guarded, but probably only by orcs.

[Legate of Amon Lanc]

Originally Posted by Rune Son of Bjarne

I personally think that there would have been other ways, but I doubt that they would have been alternatives. One could have spend ages searching for passes over the mountains and they would probably also have been guarded, but probably only by orcs.

Yeah, I think here is the answer. You have to consider the need for speed and that Frodo&co. had to know a way which would surely take them where they want, not that they find some pass and after a week of walking on the edge of exhaustion a great uncrossable fissure, or worse, an Orc tower, appears right before them. Also, remember Emyn Muil, what trouble it caused, and it was much easier terrain.
So: the passages probably have been there, but they surely could not serve good for Frodo's purposes.

[latando angaina]

you have to consider the need for speed

Considered. Liked. Bought. Playing.

Alternative ways - no.

[The Might]

You have misunderstood me Legate.
I am also asking if in general there wouldn't have been another way. Gandalf might have known as he was not too happy to hear Cirith Ungol when he met Faramir.
If we are to talk only about Frodo and Sam, I would think there was an even more important reason then their need for speed - Gollum. They now trusted him as far as leading them on the way was concerned, and they believed that Cirith Ungol was besides the Black Gate the only other way to enter Mordor.
And as Faramir and nobody else could prove Gollum wrong, they had no other way then to follow him.
But if Gandalf had remained with them, they might have taken another way I suspect.

[Legate of Amon Lanc]

Yes, I understand, I apologize, but you first spoke about the hobbits and Gollum, so I took it that you are speaking about their situation.
Anyway, you have my meaning of other ways through Ephel Dúath or Ered Lithui - since Cirith Ungol and Cirith Gorgor were the ones most used, and known (and as we can see, in case of Cirith Ungol, not so well known!), I'd suppose that there was not much else to come up with. Personally I wonder if Gandalf had even known what way they should go once they cross Anduin. The only Gandalf's words of this we have near the West gate of Moria:

'We must go down the Silverlode into the secret woods, and so to the Great River, and then -'
He paused.
'Yes, and where then?' asked Merry.
'To the end of the journey – in the end,' said Gandalf. 'We cannot look too far ahead. Let us be glad that the first stage is safely over.

I wouldn't be sure that Gandalf did not know the way to Mordor or did not plan it, nevertheless, he didn't want to talk about it, so we might just guess what plans he had. I don't know if it is safe to assume that Gandalf knew some not-so-well-guarded way through the Mountains of Shadow, even if he had wandered there once or twice, he wouldn't know if the conditions didn't change since that time. We can tell for sure that he didn't want to go through Cirith Ungol - Gandalf seems pretty startled when Faramir mentions it. I also don't know if Gandalf had some plan how to get past Cirith Gorgor, it seems rather suicidal. There will also be the possibility that he somehow thought about coming to Mordor from the northwest or south, but that is, in my opinion, not much of a good idea - this would mean a long journey through barren lands surrounded by the nations enslaved by the Enemy. Which again brings to my mind the question, if Gandalf himself did really have a plan, or if he just thought of "improvising" (for example, if the Fellowship came upon a band of Orcs on Dagorlad and took their clothes to sneak past the guards of Cirith Gorgor). Perhaps he had some preminitions that it would not be his part to choose the way to the Land of Shadow?

[The Might]

there could also be possible that he did think of Cirith Ungol himself, but only if he was there to help the Hobbits, and not if they would have been left alone with Gollum to lead them...still, considering their way on the Morgai Road there doesn't seem to be any other Orc keep in the mountains between Cirith Ungol and Durthang. There might have been small valleys made by small rivers in the mountains, as we see in the book when Sam and Frodo find a small spring after entering Mordor...so the theoretically it might have been possible.

[Legate of Amon Lanc]

Originally Posted by The Might

there could also be possible that he did think of Cirith Ungol himself, but only if he was there to help the Hobbits, and not if they would have been left alone with Gollum to lead them

Don't think so. Gandalf acts like this after hearing Faramir's news:

'Just a fool's hope, as I have been told. And when I heard of Cirith Ungol–––' He broke off and strode to the window as if his eyes could pierce the night in the East. 'Cirith Ungol!' he muttered. 'Why that way, I wonder?'

Gandalf seems rather, let's say, concerned about Cirith Ungol. Had he been a more nervous person, he'd probably say in this place something like "Oh no! Cirith Ungol! How could that fool of a Baggins even think about it!" And ending with screams of "he doomed us all, he doomed us all" he'd fall off of the balcony.

Back to reality, the possibility of taking some secret pass through the mountains seems logical, but I still can't help to doubt that Gandalf had known Mordor so well that he could come up with such a way, and as I said before, he couldn't have known if Sauron did not close that road since reocuppying Mordor (because if Gandalf even was at the borders of Mordor, I hardly believe that he did this when the Dark Lord was back there again). I remember Gandalf saying that "he visited only the older and lesser hold of the Enemy", Dol Guldur - and Aragorn seemed rather unnerved just from wandering the valley of Morgul and near the Black Gate, I doubt Gandalf ever did much more.
Maybe that idea of Orc disguise is not as bad - after all, it is a typical "heroic" way to get into the land of enemy (Beren, Finrod, Lúthien) and Frodo himself uses it in the end. I can imagine Gandalf metamorphing into a werewolf, Aragorn and Boromir masking as Uruk or Easterling warriors, Gimli as a strong Orc warrior, the hobbits becoming simple snagas (Phrodosh, Sham, Moriadog and Püpphan), and Legolas taking on a form of shadow-covered creature of dark. Then they go right through the Black Gate and straight to Mount Doom, where the last events take place.
This is the best idea I can come up with at the moment.