Over the last few days we'd had several reports from users that while their contacts were synced over to their phones, they arrived sans any phone numbers. Other attributes seemed to be communicated OK.
We have very good logging of the conversion process in our system, and though for a few reasons we don't retain logs for long, we were able to look through and spot the issue pretty quickly.
The devices have a common set of attributes which they support. The basic set of phone attributes is two home phone numbers, one mobile phone number, two work numbers, and then a handful of less common numbers such as radio phone, assistant's phone, etc.
Google, on the other hand, supports fewer categories of phone but a greater total number; someone could have five home phones, for example. This difference is where our phone mapping system comes in. The problem these users had encountered was that phones which lacked any category at all, or which were marked as 'Other' at Google, were being skipped entirely.
We are still working with this users to track down how these contacts were created--it isn't possible to add a phone number with no category through Google's own site, so it is pretty curious--but we have deployed a fix where these phones are held over in a special list until we finish mapping all the categorized numbers. If there are any free slots left in the main five (mobile, home 1 & 2, and work 1 & 2) at that time, we start using them to hold these uncategorized numbers.
The fix has been deployed as of yesterday (08/10), and so far things are looking good, as affected users have started to report they now see the phone numbers they expect.
In testing, we did find one curious related circumstance worth mentioning. On an Apple device, if one sets a phone number to the Apple 'other' category (not the same as the Google 'other' category) it isn't sent to us at all, and consequently isn't synced to Google. We'll dig into that one more deeply, but for now, we recommend not to use the 'other' category on your iPhone or iPod, or at least to understand that if you do, it won't be synced over at Google.