What about configuring your dial peer to use stcapp to the port that you want the phone to ring on. I should allow the call manager to handle the call routing, which hopefully will let the dn ring on both phones simultaneously.
Here's a section on using SCCP controlled Analog endpoints with CME.
You'll also need to setup the stcapp command, and assign the dial-peer for your 3/0 voice port to the service stcapp.
dial-peer 11 voice pots
service stcapp
port 3/0
I think this will help you do what you are trying to do..
An alternative to using the auto assign command is to manually assign ephone-dns to ephones (analog phones on FXS ports). This method is more complicated, but you might need to use it if you want to assign a specific extension number (ephone-dn) to a particular ephone. The reason that manual assignment is more complicated is because a unique device ID is required for each registering ephone and analog phones do not have unique MAC addresses like IP phones do. To create unique device IDs for analog phones, the auto assign process uses a particular algorithm. When you make manual ephone assignments, you have to use the same algorithm for each phone that receives a manual assignment.
The algorithm uses the single 12-digit SCCP local interface MAC address on the Cisco IOS gateway as the base to create unique 12-digit device IDs for all the FXS ports on the Cisco IOS gateway. The rightmost 9 digits of the SCCP local interface MAC address are shifted left three places and are used as the leftmost 9 digits for all 24 individual device IDs. The remaining 3 digits are the hexadecimal translation of the binary representation of the port's slot number (3 digits), subunit number (2 digits), and port number (7 digits). The following example shows the use of the algorithm to create a unique device ID for one port:
a. The MAC address for the Cisco VG224 SCCP local interface is 000C.8638.5EA6.
b. The FXS port has a slot number of 2 (010), a subunit number of 0 (00), and a port number of 1 (0000001). The binary digits are strung together to become 0100 0000 0001, which is then translated to 401 in hexadecimal to create the final device ID for the port and ephone.
c. The resulting unique device ID for this port is C863.85EA.6401.
When manually setting up an ephone configuration for an analog port, assign it just one button because the port represents a single-line device. The button command can use the ":" (colon, for normal), "o" (overlay) and "c" (call-waiting overlay) modes.
