The internal modem on communication adapter 2771 is set during IPL to automatically answer the phone line. If you share the phone line with other devices (like I do), then this can be very annoying. Use this tip to set auto-answer off.
Code: In order to change the configuration of the internal modem, use the modem init command string parameter (MDMINZCMD) on the Create Line Description PPP command (CRTLINPPP). In the following example, set the CMN?? parm to be the hardware resource name for your internal modem.
PCRTLINPPP LIND(NOANSWER) RSRCNAME(CMN??) INTERFACE(*INTMODEM) MDMINZCMD('ATS0=0&W0') SWTCNN(*DIAL) TEXT('Set Internal Modem To Not Answer')
This sends the AT command S0=0 (set auto-answer off) to the modem whenever the line description is varied on. However, when the system is IPL'd, the modem is restored back to factory default. I could not find this "feature" documented anywhere, but experimentation found it to be true. To overcome this, I added the following three lines to my startup program (you know, the program specified by system value QSTRUPPGM).
VRYCFG CFGOBJ(NOANSWER) CFGTYPE(*LIN) STATUS(*ON)
VRYCFG CFGOBJ(NOANSWER) CFGTYPE(*LIN) STATUS(*OFF)
Now each time the system is IPL'd, the NOANSWER line is varied on then off, and the modem will not answer incoming calls.