Only 1st page of sent fax received by vendor

We send faxes on Windows XP (Fax Console) using a US Robotics 56K external modem. We use Lawson/Infor's Fax Integrator system to send purchase orders to various healthcare vendors. Most faxed POs are sent w/o issues.

We have some vendors that only receive the 1st page of the PO (most POs are 2 pages in length). The 1st page doesn't include any of the ordered items' detail, so the vendor has no way of knowing what is being ordered.

We have the Fax Integrator set up to retry sending a fax up to 6 times if it is unsuccessful in sending the fax. So in this case, the 1st page is sent to the vendor but something causes a disconnection. Then the Fax Integrator thinks that it needs to try again. Long story short, it ends up sending the 1st page of the PO 6 times for some of the vendors.

To me, it appears that we are sending the faxed PO successfully but something on the vendor's side is causing it to disconnect. Any thoughts on how to resolve this? Is there something the vendor needs to do in their modem settings to resolve this?