Cisco 887VAG - Unable to get the 3G working

Today I was tasked with configuring a Cisco 887VAG's 3G interface... and had some issues. Here in Australia I've done plenty of 3G on Cisco router configurations so this one kind of frustrated me a little
The basics of the issue are that the Cisco 887VAG doesn't seem to support "encapsulation ppp" even though the router happily accepts the command.
The configuration for most 3G varieties with Cisco looks something like the following:

TEST#

cellular 0 gsm profile create 1 <APN> chap <username@domain.com.au> <password>

TEST(config)#
chat-script gsm "" "ATDT*98*1#" TIMEOUT 60 "CONNECT"

!

interface Cellular0

description NextG Modem Dialer Interface

no ip address

encapsulation ppp

dialer in-band

dialer pool-member 1

async mode interactive

!

interface Dialer1

ip address negotiated

ip virtual-reassembly

encapsulation ppp

dialer pool 1

dialer idle-timeout 0

dialer string gsm

dialer persistent

dialer-group 1

no fair-queue

no cdp enable

ppp chap hostname <username@domain.com.au>

ppp chap password <password>

ppp ipcp dns request

!

!

ip route 0.0.0.0 0.0.0.0 Dialer1 250

!

!

access-list 1 permit any

dialer-list 1 protocol ip list 1

!

!

line 3

script dialer gsm

no exec

transport input all

transport output telnet

In the above, you have a 3G profile, a cellular interface and dialer interface all joined together. On the 887VAG the encapsulation ppp command spat out an issue as follows:

TEST(config)#int cell 0

TEST(config-if)#encapsulation ppp

Cellular0: Only SLIP encapsulation supported

Without PPP we can't authenticate. Without authentication... it won't allow me to connect. Regardless, I couldn't find much information out there on this specific issue so I thought a blog entry would be handy. I've got a TAC case lodged with Cisco now... will update as more information comes to hand.
The Cisco 887VAG is running:

TEST#show ver

Cisco IOS Software, C880 Software (C880DATA-UNIVERSALK9-M), Version 15.1(4)M3, RELEASE SOFTWARE (fc1)

Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2011 by Cisco Systems, Inc.
Compiled Tue 06-Dec-11 22:52 by prod_rel_team
ROM: System Bootstrap, Version 15.1(2r)T2, RELEASE SOFTWARE (fc1)

TEST uptime is 1 hour, 11 minutes
System returned to ROM by power-on
System restarted at 00:56:10 UTC Mon Apr 2 2012
System image file is "flash:c880data-universalk9-mz.151-4.M3.bin"
Last reload type: Normal ReloadTEST(config)#int cell 0

=======================================

Update 1:
As John Marshall indicated in the comments below, there is a configuration guide available from Cisco here. I was directed to that guide by TAC just over the last week or so. I've had some delays with getting through to TAC for me due to SmartNet coverage and so forth.

For me, the guide indicated didn't work.... I have several devices all fresh from factory. I tried setup a second 887VAG with the guide configuration from scratch like for like to what John did and still no go.

I'm making some progress with TAC now... we will see how we go. Oh, and the SIM definitely works (it was confirmed on a 887G on my desk using the old style configuration security).

This isn't all to say I haven't been making "some" progress though. The cellular interface on the new routers "HAS" to be slip encapsulation. It is just the way the new modem interfaces with the chassis. Refer to the configuration guide from Cisco for more information on that.

I'll probably write another post with configuration/troubleshooting steps once I get it sorted completely... for the moment I'm still stuck but am working with TAC to get this resolved.

For the meantime here are some useful commands:

• debug cellular 0 messages all - If you want to see if the cellular interface is doing "something" chuck this command in to have a look at the back/forth between the cellular interface and the cell tower.
• show cell 0 radio history all - This shows you RSSI history on the modem much like "show proc cpu history" shows you CPU loading history. Cool.
• debug ppp negotiation / debug ppp authentication - In theory (at least on the old routers) these commands were useful because they confirmed either you were at the PPP level of the connection. I'm not sure if these work on the newer models though... yet. I plan to find out.

Useful information:

• The cellular profile referenced by the "AT" command seems to still be configured using the "cell 0 gsm profile create" command according to the guide
• The chat-script line referenced by the old (AT98*1)/new (AT!SCACT=1,1) routers differs but achieves the same thing. These are the AT commands the chassis runs to initiate a connection on the onboard Sierra Wireless card to connect using a profile. The differences are mainly cosmetic and you shouldn't need to tinker with them beyond defining "1" as the profile.

What I am thinking:

• At the moment if I telnet into the modem itself (you shouldn't need to do this) and run the AT command specified by Cisco's guide I get an error:
  
  Router#telnet 1.1.1.1 2003
  Trying 1.1.1.1, 2003 ... Open
  AT!SCACT=1,1
  +CME ERROR: no network service
  Now I also tried creating a profile on the modem itself using AT commands that specified PAP authentication... and when I ran the AT command described above "OK". Which means "successful". Frustrating. (I've been careful to only play with AT commands on one device in case it breaks it)

I'll continue to work through with Cisco...

=======================================

Update 2: Resolution
In the end the Cisco provided configuration in the link above (or in comments) is correct. Use that configuration. My issue was related to the cellular profile not being the correct type. Telstra need IPv4 type profiles for internet. I was configuring PPP type profiles. I will write up a more detailed guide at some point.