Periodic breaks in communication (modem ZTE MF 667)

If you create access to the Internet using usb modem ZTE MF667 then the network periodically breaks.
After connecting the modem ZTE MF 667 works extremely unstable. If when loading using a torrent client then the network is stable, if you just look for information on the Internet, that is not stable (that disconnection occur very
often).

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: network-manager 0.9.8.8-0ubuntu5
ProcVersionSignature: Ubuntu 3.13.0-23.45-generic 3.13.8
Uname: Linux 3.13.0-23-generic x86_64
ApportVersion: 2.14.1-0ubuntu1
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Apr 8 16:49:01 2014
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2014-04-06 (2 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Daily amd64 (20140405)
IpRoute:
 default via 10.64.64.64 dev ppp0 proto static
 10.64.64.64 dev ppp0 proto kernel scope link src 10.39.225.164
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=false
 WWANEnabled=true
 WimaxEnabled=true
SourcePackage: network-manager
UpgradeStatus: No upgrade log present (probably fresh install)
nmcli-nm:
 ** (process:23293): WARNING **: Could not create object for /org/freedesktop/NetworkManager/Settings/2: uid 1000 has no permission to perform this operation

 ** (process:23293): WARNING **: handle_property_changed: failed to update property 'available-connections' of object type NMDeviceModem.
 RUNNING VERSION STATE NET-ENABLED WIFI-HARDWARE WIFI WWAN-HARDWARE WWAN
 running 0.9.8.8 connected enabled enabled disabled enabled enabled