They got the distress signal sent by Alissa. Nicole's was just personal message for Isaac, and he joined USG Kellion crew because of that message. Not sure how that happened that he hasn't watched it to the end until the last chapters of the game though, so correct me if I'm wrong.
Alissa mentioned in her distress call that she may be the sole survivor. But the crew of USG Kellion, in the beginning of DS1, seemed completely unaware of that. Moreover they seemed completely unaware of the outbreak.
the beginning of dead space is a bit strange: the Kellion comes to repair the Ishimura, and the message of NIcole worries Isaac but it doesn't mean the ship is in danger for them (could be her own mental disease). They are suprised that nobody comes to check their (rough) arrival. Apparently, despite fighting the necromorphs for hours, the crew didn't have the time to precise in their call for help that the entire ship was invaded by tons of FUCKING ZOMBIES and the company should send all the marines army (but even the USM Valor was not enough eventually, so Isaac was maybe the best assistance already, lol).
I'm sure that Alissa's beacon did not work at all, because nobody on board of Kellion did not read it's signal. They spoke about "total communications blackout" - it mean that there were no messages picked from ship. But I got a question about signal they recieved during approach (which they mistaken as problems with encoder). Please, say what do you think about it? I have these ideaz:
1) It was actually signal from Allissa's beacon - malfunction made it not-readable. If so - why they did not understood that source is not a Ishimura herself, but something near the ship.
2) It was a sound of Necromorphs horde. Signal was not open-microphone broadcast and taken just a few seconds. If so - who did send it? Kyne? Temple? (we know that Necromorphs are not so smart to use advanced equipment like radio, so it got to be human to send signal). And in this case did Kendra initially properly understood signal (she came to get Marker as we know)?
3) It was a message from someone on board of ship to ask for help (like SOS), or, controversly, not to approach infected ship. In this case it mean that distortion of signal caused by damaged radio equipment. Also it mean that Kendra did not know that ship is infected and said truth about equipment problem. For this version - the fact that comms were damaged and fixed by Isaac later.