My `/etc/netctl/mobile_ppp` file's contents are as follows:

Description='Example PPP mobile connection'
Interface='ttyUSB0'
Connection='mobile_ppp'
PhoneNumber='*99#'
# Use default route provided by the peer (default: true)
#DefaultRoute=true
# Use DNS provided by the peer (default: true)
#UsePeerDNS=true
# The user and password are not always required
#User='example@yourprovider.com'
#Password='very secret'
# The access point name you are connecting to
AccessPointName='internet'
# If your device has a PIN code, set it here. Defaults to 'None'
#Pin=None
# Mode can be one of 3Gpref, 3Gonly, GPRSpref, GPRSonly, None
# These only work for Huawei USB modems; all other devices should use None
Mode=3Gonly
# ^ tried all other options too