Here is where to find chipset information on various embeddable modems.

Here is a link to the 33.6 k/s product.

For small volume I would not be surprised if you find the system cost of building the discrete modem from the chipset and DAA to be close to the cost of a socket modem. Plus the discrete solution will require type approvals in all countries you wish to sell your product. Some of the socket modems come with a type approval sticker ready to paste on the back of your box.

Michael Karas