Take a look at this, it uses a VCalendar-approach to acheve the contact-storing from a web-page.
Full code example quoted here:
<?php
# Send correct headers
header("Content-type: text/x-vcalendar; charset=utf-8");
# Alternatively: application/octet-stream
# Depending on the desired browser behaviour
# Be sure to test thoroughly cross-browser
header("Content-Disposition: attachment; filename=\"iphonecontact.ics\";");
# Output file contents - simple version
#echo file_get_contents("iphonecontact.ics");
# Generate file contents - advanced version
# BEGIN:VCALENDAR
# VERSION:2.0
# BEGIN:VEVENT
# DTSTART;TZID=Europe/London:20120617T090000
# DTEND;TZID=Europe/London:20120617T100000
# SUMMARY:iPhone Contact
# DTSTAMP:20120617T080516Z
# ATTACH;VALUE=BINARY;ENCODING=BASE64;FMTTYPE=text/directory;
# X-APPLE-FILENAME=iphonecontact.vcf:
# QkVHSU46VkNBUkQNClZFUlNJT046My4wDQpOOkNvbnRhY3Q7aVBob25lOzs7DQpGTjppUGhvbm
# UgQ29udGFjdA0KRU1BSUw7VFlQRT1JTlRFUk5FVDtUWVBFPVdPUks6aXBob25lQHRoZXNpbGlj
# b25nbG9iZS5jb20NClRFTDtUWVBFPUNFTEw7VFlQRT1WT0lDRTtUWVBFPXByZWY6KzQ0MTIzND
# U2Nzg5MA0KRU5EOlZDQVJE
# END:VEVENT
# END:VCALENDAR
echo "BEGIN:VCALENDAR\n";
echo "VERSION:2.0\n";
echo "BEGIN:VEVENT\n";
echo "SUMMARY:Click attached contact below to save to your contacts\n";
$dtstart = date("Ymd")."T".date("Hi")."00";
echo "DTSTART;TZID=Europe/London:".$dtstart."\n";
$dtend = date("Ymd")."T".date("Hi")."01";
echo "DTEND;TZID=Europe/London:".$dtend."\n";
echo "DTSTAMP:".$dtstart."Z\n";
echo "ATTACH;VALUE=BINARY;ENCODING=BASE64;FMTTYPE=text/directory;\n";
echo " X-APPLE-FILENAME=iphonecontact.vcf:\n";
$vcard = file_get_contents("iphonecontact.vcf"); # read the file into memory
$b64vcard = base64_encode($vcard); # base64 encode it so that it can be used as an attachemnt to the "dummy" calendar appointment
$b64mline = chunk_split($b64vcard,74,"\n"); # chunk the single long line of b64 text in accordance with RFC2045 (and the exact line length determined from the original .ics file exported from Apple calendar
$b64final = preg_replace('/(.+)/', ' $1', $b64mline); # need to indent all the lines by 1 space for the iphone (yes really?!!)
echo $b64final; # output the correctly formatted encoded text
echo "END:VEVENT\n";
echo "END:VCALENDAR\n";
?>
(Original answer by Steve Grobe - iPhone: how to get safari to recognize a vcard? )