Using pppd(8)

The configuration for use with pppd(8) needs three files:

/etc/ppp/peers/umts   - the file with the options for pppd(8)

/etc/ppp/peers/umts.chat   - the chat script to be used to talk to the modem

/etc/ppp/pap-secrets    - our password file

Using ppp(8)

very good example for GPRS / UMTS connections in
           /etc/ppp/ppp.conf.sample