I wrote down 110 of the phone numbers in case of any possible mistakes and dialed them on agent ray's phone and just thought i would share the numbers in case it helps someone.
Edit: Thanks to
Shadow XBL for letting me know 5449 doesn't work (I will put strikethroughs on any wrong numbers)
2nd edit: Thanks to VaderBox for confirming you can work on this throughout the game in different locations. Also thanks to Basileus for correcting the wrong number (5449) which is actually (5459) which i have now changed.
3rd edit: Thanks to A1ienspacebats and ChooseMyFate for stating in the comments that you can hang up the phone after the voicemail and dial the next number without exiting the screen and having to use the phone again. Just push the button at the top of the phone and dial the next number.
5131 8735 5094 6103 7202 6407 6272 8630 5275 4580
2695 1430 3233 3242 3989 5133 7443 6841 1786 6769
6948 6701 6855 2062 5506 6842 8151 5523 2229 5018
1197 5485 8532 8302 6674 7057 8425 6588 1806 3558
3597 4598 5755 4235 2552 4828 7283 4249 7425 3091
4222 4785 6216 8670 6594 2977 5186 4972 5797 8044
3764 5692 1584 5322 5982 2017 5420 8461 6147 3355
4171 4476 5459 1184 3579 3660 4628 4540 2270 4250
4624 6928 3321 4934 4821 4939 1573 3259 8949 6906
1477 3078 1220 1792 7142 1428 3620 5368 4636 2594
3836 2212 2461 5690 7347 8004 1004 5851 8318 1659
I imagine you could do this at any point as agent ray even at the very start of the game but i rang the numbers on B street so cannot confirm for sure.
This can also be worked towards on the Delores flashback, you also do not have to listen to the full message for it to count, but i had the achievement tracker on just to be sure.
I am new to guide writing so will be willing to edit or credit any information that may be of help to others.
Thanks achievement hunters.