Frequently asked questions - QuesCom
[2006-05-10]
The most frequent questions about QuesCom, which have been asked by our customers.
- What is a GSM Gateway?
- Why you should always include a QuesCom 400 GSM in your design?
- How many GSM channels do I need?
- How do I integrate the QuesCom 400 GSM with my PBX?
- What features are available for Outgoing Calls?
- What features are available for Incoming Calls?
- How can I use the QuesCom 400 to do callbacks?
- How can I send SMS using the QuesCom 400 GSM?
- How can I manage QuesCom 400 GSM?
- What is the QuesCom 400 GSM’s Technical Specification?
- What are the functional additional features available?
A GSM gateway connects to a PBX and handles calls directed to cell phones. It can also function in reverse fielding incoming calls from the GSM network to the PBX. The QuesCom 400 GSM gateway may have between 4 and 8 GSM modules and each module is one GSM channel and hence one active call.
The QuesCom 400 GSM is connected directly to the PBX using either the existing ISDN trunk in a pass-through configuration or using a separate dedicated PRI or 1-4 BRI links. In the pass-through configuration it is immediately operational and in the dedicated version it is operational as soon as the redirection parameters have been defined in the PBX – thereby dramatically reducing the level of network downtime associated with traditional communications network upgrades. The product offers a range of PBX services – these include hold, call forwarding, transfer and conference calls and an IVR, and are available for calls to and from GSM mobiles.
Surveys have discovered that a typical enterprise will have between 25% and 50 of monthly phone bill consist of calls from landlines to mobile numbers. By cutting the cost of these calls by at least 50% and sometimes up to 90% the GSM gateway immediately provides a tangible benefit for the customer. Typical enterprises will receive savings many thousands of Euros a year and typical payback periods for the ISDN gateway are in the range of 4-6 months. In addition to this primary benefit the GSM gateway has many additional features that will assist customers such as SMS handling and VOIP gateway capability.
This is a question that can only be answered accurately with feedback from the customer on his calling patterns, however a rule of thumb indicates that one GSM channel is suitable for about 50 people. Thus small enterprise of 150-200 people would need 4 GSM channels. However it is important to consider the job type and industry when calculating this. An office that supports many mobile workers (such as a construction company or transport firm) may see the ratio as low as one channel per user whereas a call-centre that mainly calls out to land lines might see a ratio as low as one for every 100 people despite having many more people totally. Offices that support many mobile professionals such as sales-people or consultants typically need a higher ratio than those who have little external contact. However, having said that some sites may surprise – for example schools often need to contact parents and the parents frequently give them a mobile number to call.
Typically the simplest method of sizing is to look at the monthly phone bill and see how many minutes of calls to cellular networks there are. From this number we can use the table below to estimate the number of channels required:
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Minutes/month
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Channels required
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1 500 – 8 000
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4
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8 000 – 18 000
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6
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18 000 – 28 000
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8
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28 000 – 40 000
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10
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40 000 – 52 000
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12
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For customers with 52 000 minutes or more we recommend contacting QuesCom to give a better sizing estimate as the number will be heavily dependent on the number of users at the site or sites.
There are a variety of different options to connect the QuesCom 400 to the PBX. The choice depends on the total call volume out of the PBX and the expected call volume to/from GSM. The availability of ports in the PBX may also have an effect. Essentially there are 4 options:
• PRI Pass-through
• Dedicated PRI
• Dedicated BRI
• BRI Pass-through
As a rule of thumb pass-through configurations are recommended when the number of GSM calls is 25% or less of the total number of external calls. When the GSM percentage rises above 25% then it is typically better use a dedicated channel to the GSM gateway since otherwise there is high probability that incoming landline calls will be blocked by GSM calls.
The choice of BRI vs. PRI is typically dependant on the PBX size and configuration; there are two cases where BRI interfaces are recommended. The first is for small sites where the entire interface to the outside world is via BRI and the second is the case where the PBX has sufficient spare BRI ports but would require an additional interface cards to be purchased to connect via a PRI.
In pass-through configurations the QuesCom 400 is completely transparent to the PBX, except for increasing the number of channels available on the link. All routing decisions are made on the QuesCom 400 and advanced features such as Callbacks and IVR functionality all take place without any interaction with the PBX. In dedicated trunk configurations the PBX must be reconfigured to route appropriate calls to the QuesCom gateway(s).
For large GSM call volumes (i.e. ones that indicate a requirement for more than 8 GSM channels) it is possible to stack QuesCom 400 gateways on a dedicated PRI interface. A total of 4 QuesCom 400s may be stacked on a PRI since each QuesCom 400 may service 8 GSM calls simultaneously. In cases where the PBX has multiple trunks to the PSTN it may be preferable (and provide considerable savings) to remove one trunk from the PSTN and dedicate it to the QuesCom 400 stack. In this case it will of course be necessary to calculate the expected landline call volume to confirm that sufficient channels are available.
Since the entire path of the call is digital, when making calls to GSM handsets there is no degradation of voice quality and no echo or other issues. Combined with the high-quality antennae provided with the QuesCom 400 and the flexibility of their positioning, the quality of calls to GSM handsets depends solely on the cell quality of the receiving handset.
The QuesCom 400 continuously monitors the availability of the local GSM network(s) and cell(s), thus in the event of temporary network problems redirection via alternative access methods such as another GSM gateway in a different location or to the PSTN is both immediate and automatic, just as occurs in the event of device failure within the gateway.
Telephony services and features available to standard calls are also made available for calls to GSM handsets such as:
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Music on Hold
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Call transfer
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Redirection
In addition the QuesCom 400 may be configured to either present the SIM Cards number to the network or to hide it.
If the GSM gateway has SIM from multiple GSM networks or with different contracts and tariffs then selection of which operator to use may be made based on a number of criteria:
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Based on partial number routing (e.g. all numbers beginning 071 to use cards 1-4, all numbers beginning 072 to use cards 5-8 etc.)
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Based upon a list of numbers for each carrier. (e.g. Calls to 0712345678 and 0712345987 use cards 5-8 0723459678 and 0723459178 use card 4)
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A combination of the above
The table may be either created manually or imported from a text file using the administration utilities.
QuesCom 400 can handle incoming calls in a variety of ways depending on how it is configured but subject to certain technological limitations. It is impossible to group GSM SIM cards so that they share a number, thus if a SIM card is already in use when it receives a call the ability to redirect that call to another number is dependant on GSM operator and the contract under which the SIM card is operating.
Since the GSM gateway's SIM card numbers are the ones presented to mobile recipients of calls, if a mobile users returns the call they will call the gateway. The gateway can either direct the call to the last number that called the GSM number or it can pass the call to the built-in IVR or receptionist.
The built-in IVR (Interactive voice response system) allows a caller to choose from a wide variety of options such as checking voicemail, calling a colleague and so on.
A mobile user may call a special number on the QuesCom 400. The user is recognized by its GSM number as being authorized to receive a call back – the call he makes is rejected thus incurring no cost. However, the GSM gateway then calls the mobile user back and either then presents the mobile user with an IVR menu or directly connects him to a known party on the other end – no matter whether the other party is reachable in the office or only on his mobile phone.
Example:
A company salesman calls the number of an administrator at his office. The GSM gateway detects the call, terminates it and simultaneously calls both the salesman and the administrator. This means that instead of the conversation being charged at the rate of mobile-landline, the call is charged as mobile-mobile.
QuesCom 400 GSM can be configured to receive emails in a particular format. These emails will then be converted to SMS and sent.
QuesCom 400 GSM gateway may be managed using a serial port, a telnet interface, a built in Web (HTTP) interface called Q Portal or by using a Microsoft Management Console application (Q console).
Although all functions are available via the console access CLI this is not the recommended method of administration as the graphical methods are more efficient.
The Q console (a Microsoft Management Console application) allows administration and management of all facets of the QuesCom 400 GSM.
- Q portal (Web Interface) administration
The Q portal interface permits configuration of the more commonly modified features of the QuesCom 400, however less frequently modified options such as CODEC type must be modified using either Q console or the CLI interface. The Q portal interface is accessed via port 8080
- Reports Logs and Statistics
Details of all calls handled by the QuesCom 400, irrespective of origin, are stored in the CDR (Call Detail Record) database. The details recorded are the called and calling party numbers, the date and time of the call and its status (call connected, no response, engaged…)
This CDR database is stored in Microsoft Access format and may be retrieved two ways:
- Directly via the Q portal (Web Administration) Interface. Summary views are available and a number of more detailed filters can be defined.
- All data may be exported to a third party application and/or emails may be sent automatically to forward the database to an administrator according to a predetermined timetable.
The calls may be filtered with the information fields as follows:
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Origin and Destination of call
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PABX, PSTN or other network or element connected via ISDN interface
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GSM Network
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Voice over IP network: any element connected via the voice over IP interface (server, gateway or IP telephone)
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CTI Application (click to call, call automation, voicemail server)
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Called and calling party numbers
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Number before and after LCR (least cost routing) manipulation
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Time and date of start and end of call
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Type of call failure from the table of failed calls
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Type of call (ISDN, VoIP, CTI,…) and channel usage details for the ISDN and GSM cards
For a financial report of communication costs QuesCom recommends automatically forwarding the call statistics via email to an external application such as QuesCom GeoTaxe, Servatel or their OEM versions (such as ExperTaxe).
When a user makes a call the gateway may be configured to send the user the GSM Call Progress Tone to indicate that a subsequent call failure is due to the events in the GSM network or at the called-party.
All errors are visible through the Microsoft Management Console. The gateway also has an SNMP MIB and can send SNMP traps to network management devices if configured. In the event of overheating (for example due to fan failure) an audible alarm sounds on the device.
QuesCom 400 GSM has the following specifications.
Interoperability and Compatibility
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GSM
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All SIM types and both European bands - GSM 900 and DCS 1800
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Interfaces
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4 x BRI or E1 PRI
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Network
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10/100 Ethernet auto sensing
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Management
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Serial Console, Telnet, HTTP and Microsoft Management Console
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Dimensions & weight
400 mm W x 325 mm D x 45 mm H
17.3" W x 12.8" D x 1U H
19" Rack Mountable, max. 8 kg
Power requirements
Auto ranging Power Supply 100-240 V AC
150 VA per QuesCom 400
Heat Dissipation: 500 Btu per hour
MTBF: 40.000 h (Mean Time Between Failures)
QuesCom 400 is not just a simple GSM gateway or voice integration platform. It also offers additional features that can meet the market needs:
- Voice Box – advanced voice mail system. Message can be listened on through the phone or sent as a attachment of an e-mail. Voice mail calls are forwarded according to scheme that is configured by the user.
- Fax Server – device recognizes fax carrier, converts data into graphic file (TIFF format), and sends to defined user or user group as an e-mail attachment. QuesCom Virtual Printer is used for fax sending directly from Windows applications such as text, graphic editors, etc.
- IVR – Interactive Voice Response – automatically distributes calls according to scheme without employee engagement. Customer is guided by prerecorded voice messages and by use of keypad finally reaches the chosen destination. During call redirection, customer can accept or decline proposed call route, move back to the beginning of the call route.
- Call-back – within this feature, an unique Caller ID (mobile or fixed extension) can be defined in Call Server. When this Caller ID reaches gateway, call is dropped and then QuesCom dials Caller ID and makes connection with specified number – Caller ID extension is not charged for its call.
- SMS Gateway – this feature enables SMS sending through the call server. It supports both – incoming and outgoing SMS. It allows to improve efficiency of monitoring or alarming system.
- CTI Interface - Computer Telephone Integration Interface - integrates call server with office applications such as: Microsoft Outlook, Lotus Notes, Microsoft Exchange or any ODBC compliant databases.
- LCR – Least Cost Routing – call server chooses the cheapest call route based on destination number (prefix called): GSM gateway, fixed line or VoIP operator, daytime.
