This message was intercepted between two well known hackers in 1999. No one has been able to decrypt it since then. Can you do it?

Upon playing the attached audio file, we hear a series of touchtones on a keypad. After some searching, i found that this is DTMF (dial tone multi frequency) file. Using an online dtmf decoder, i decoded the dialtones into their respective numbers. We get this:

44488933999344555777744345333777744662555555355333222444

Now, i opened the file in Audacity and found the positions of gaps in the audio files, indicating a pause. Finally, after inserting the spaces in the right positions, we get

444 88 9 33 999 3 44 55 5 7777 44 3 4 5 333 7777 44 66 2 555 5 55 3 55 333 222 444

Now, simply typing out the above sequence on a 1990s keypad yields the flag:

iuweydhkjshdgjfshnaljkdkfci