Are there any computer vendors (like Dell, Lenovo, or..) that still sell laptops with an internal serial port?

We are using several modem and other kind of box at work that have to be used (and/or programmed) with serial port (RS232, DB9, ..). We tried many usb/pcmcia serial adapter which run fine when used to load programs on the boxes but not with modems. The protocol behind the RTC connection (with modem) need timer we are not able to reach when using an adapter (maybe until we find a very good adapter), and that leads to my question..