On the newer 3G cards (e.g. PCEX-3G-HSPA-R6 and HWIC-3G-HSPA) there is a new option for PDP Type in profile creation.
Previously, the profile was created with PDP Type IPv4 only, now we can choose between PPP and IPv4.
cellular x/x/x gsm profile create <number> <apn> [IPv4|PPP] [chap|pap] <username> <password>
The only operator known to use PDP Type PPP is DoCoMo in Japan. Anywhere else, you will need to use IPv4.
If you configure PPP and your operator does not support it, the link will not come up and the profile will remain inactive.
The PPP option in PDP type is not related to the PPP configuration under cellular interface, and should not be confused.
Although we configure PPP in the cellular interface (and CHAP/PAP credentials in the profile), this PPP communication is local, and it is used only between IOS and the modem.
It does not extend all the way to the mobile operator network.
The modem will communicate with the network using PDP.
See Figure7 from Configuring 3G Wireless WAN on Modular and Fixed ISRs :
You can verify the profile configuration by using "show cellular x/x/x all"
Profile 1 = INACTIVE*
PDP Type = PPP <<<<<<<
Access Point Name (APN) = myAPN.com
Authentication = CHAP
Username: guest, Password: guest
To change the PDP type you need to delete the existing profile, then create a new one with the right PDP Type:
cellular x/x/x gsm profile delete <number>
UPDATE: Listening to feedback from outr customers, the syntax for this command has been changed, moving the pdp-type option to the end of the command.
In this way, the PDP-type will be an optional argument, set by default to IPv4. The change has been introduced by DDTS CSCtj52268.