Description Title of Invention: COMMUNICATION SYSTEM AND APPARATUS FOR STATUS DEPENDENT MOBILE SERVICES Technical Field fOOOll This invention relates to the field of telecommunications in a packet-switched data communications network. More particularly, it concerns the mobile terminal with local connection to other devices. Background Art L0002J The cellular telecommunications has been under constant evolution, from the earlier days of GSM (Global System for Mobile communications) networks, to GPRS (General Packet Radio Service), to the modem system of UMTS (Universal Mobile Telecommunications System) which can be found in various big cities around the world. In the very near future, the next generation Long Term Evolution (LTE) networks are going to be deployed. Along with access technologies, the services provided by the cellular telecommunications network have also been evolving. [0(X)3] Today's cellular network is no longer providing only rudimentary voice call services, but also short text message transmission and access to the global Internet. Recently, new services have even been expanded to cover non-human communications, such as machine-to-machine (M2M) communications. The Third Generation Partnership Project (3GPP) has started defining the requirements for a cellular network to support machine-type conununications in [Non-Patent Document 11. This will make the cellular network even more suitable to support machine-type communications. [0004] Machine-type communications can cover a very wide range of appUcations, from measurement collection from sensors, to remote control of devices. There are a lot of examples which employ cellular networks. For instance, [Patent Document 1] discloses an asset management architecture utilizing cellular networks to control remote assets, such as automatically-operated vehicles. In [Patent Document 31, a system which uses a regular cellular mobile phone to control an automobile is also described. [0005] The services provided by cellular conununications system are also getting more specific. For instance, some services provide location specific information to the user. This will involve the network obtaining the current location of the mobile phone (or user equipment, UE, in 3GPP terminology) using technique such as those disclosed by [Patent D(x;ument 2], [Patent DcKument 4], and [Patent Document 6]. It is also possible for the network to maintain a presence server, such as described in [Patent Document 7]. By exposing the presence information to application servers through methods taught by [Patent Document 5], the application servers can tailor information according to the present location of the mobile phone. Citation List Patent Literature [00061 [PTL 11 US Patent 7356494B2 Ehnnan et al., "Robust Wireless Communications System Architecture and Asset Management Applications Performed thereof", Apr 2008. [PTL 2] US Patent Application US 2008/0162637A1 Adamczyk et al., "Application Services Infrastructure for Next generation Networks including Notification Capability and Related Methods and Computer Program Products", Jul 2008. [PTL 3] PCT Patent Application WO 2008/079254A1 Mikan et al.. "Wireless Device as Programmable Vehicle Key", Jul 2008. [PTL 4] US Patent Application US 2007/0005188A1 Johnson, W., "System and Method for Proactive Content Delivery by Situational Location", Jan 2007. [PTL 5] US Patent Application US 2006/012969lAl Coffee et al., "Location Aware Wireless Data Gateway", Jun 2006. [PTL 6] PCT Patent Application WO 2006/023225A1 Julka, V, and Colban, E., "Re-sponsive to Receiving an Event Notification Sent by a MSC, Managing Commu-nication Resources in a Packet Switched Network", Mar 2006. [PTL 7] PCT Patent Application WO 2002/096128 A2 Kiss et al., "Presence Server in IP Multimedia", Nov 2002. Non Patent Literature [00071 [NPL 11 3GPP TS 22.368v0.4.0, "Service Requirements for Machine Type Commu¬nications", May 2009. [NPL 21 3GPPTS 23.401v9.3.0, "GPRS enhancements for E-UTRAN access", Dec 2009. [NPL 31 3GPP TS 36.413v9.1.0, "E-UTRA SI Application Protocol", Dec 2009. [NPL 41 3GPP TS 36.423v9.1.0, "E-UTRA X2 Application Protocol", Dec 2009. Summary of Invention Teclinical Problem [0008] However, some services may require that the UE constantly moves from idle mode to connected mode, such as requiring the mobile phone to update its location status to ad¬ditional servers or responding to queries that may not need immediate replies, thereby wasting the mobile phone's battery. Some require the use of Session Initiation Protocol (SIP) for presence signalling, thereby increasing the cost of implementing such solutions. In addition, some services are specific to the status of the mobile phone such that it is meaningless to provide the service to the mobile phone when the mobile phone is not in the required status. This means that UE needs to change its state from 3 idle mode to connected mode in order to inform the status as presence information on the UE to the server. It may cause wastage of the mobile phone's battery. [0009] One example scenario is the use of the mobile phone in an application of smart grid utility, where the power grid provider uses specialized server to communicate with home appliances. This is done not only to collect power consumption statistics by in¬dividual home appliances and household, but also to provide power usage profiles and hints to these devices so that power consumption can be optimized based on the demand and supply of the power grid. Since most of such home appliances (eg, air-conditioner, refrigerator) would not have a SIM hosting circuitry built-in, the mobile phone may be employed to use the cellular netwoik as the transport medium for the smart grid M2M application. [0010] With the ubiquity of cellular phone, one can safely assume each household to have at least one subscriber of the cellular network. The home appliances can connect to the subscriber's mobile phone using local network technology such as WiFi or Zigbee, and then make use of the cellular network to communicate with the smart grid utility provider. This has a few advantages. Firstly, there is no need for home appUances to have their own cellular access mechanisms. Secondly, when the subscriber is not at home, the home appliances would either be turned off or in low-power mode anyway, hence there is no real need for the smart grid provider to communicate with the home appliances. The only time when such communications are necessary is when the subscriber is at home - and so would be the phone. [0011] This seems like a win-win arrangement, except that there is one disadvantage: the impact on the battery life of the mobile phone. When the mobile phone is back at home, it can obviously be docked and draw power from the mains, so battery life is of no concern then. However, when the mobile phone leaves the house, it will lose the connection to the home appliances and then will be on battery power. But the smart grid utility provider does not know this. It will continue to contact the mobile phone to collect power consumption statistics information from the home appliances and to send energy usage profiles and hints to the home appliances. This is a waste of the mobile phone battery life since the any such communications attempt is a waste, as the mobile phone is not connected to the home appliance. [0012] Another example scenario is that it may also be possible for servers handling the M2M device to query these M2M devices. There may be different type of such queries. Some queries may need an immediate reply such as current temperature needed. Some may not need an immediate reply such as periodic software update. But the current mechanisms specify that UE is made to reply regardless of the current UE state - idle or connected. Also, the asking entity, either sei-ver or other devices have no in¬formation of whether the UE is in idle mode or not. Whether the UE is in idle mode or not is known only by the UE and the network node. vSo what we can imagine happening is that the UE is woken up each time someb