Gray, GSM, white, premium, CLI, direct, standard voip routes? What does it mean?

Gray, GSM, white, premium, CLI, direct, standard routes? What does it mean?

Be careful when buying voip accounts or routes. Do not let yourself be cheated.

VOIP is a very attractive and commun technology, allowing great savings of money, flexibility and provides multiple value-added services in telecommunications.

In the market there are a great variety of offers with prices that can be very differents for the same destination. For example a provider1 website can offer calls to Chile with a price per minute of 1 cent of dollar to all operators, while another page could show a much higher price and even discriminate price by localities or operators within the same country Chile. Why such a big difference in price?

These large price differences are usually due to different quality on call termination routes. There are even websites that offer unlimited calls to dozens of countries for incredibly low prices; After a while they disappear the web pages and also the money or balance of their clients; A very common type of fraud!

Here are some common situations that can help identify the quality of voip providers and thus avoid fraud or frustration when using this technology.

The various VoIP providers use terms such as “gray routes”, “GSM route”, “white route”, “premium routes”, “CLI routes”, “direct routes”, and many other terms that make users confused.

We include this post in order to create the discussion that allows Users to get the best of voip technology.


It is often called gray to what is not white (legal) or black (illegal). Generally, they are calls terminations using regular mobile phone lines (SIM cards) or by using fixed lines (which have no legal authorization for such traffic).

Advantages for users with gray routes:

– Extremely low per-minute prices

– Possibility to find free destinations to several countries, even unlimited plans.

– Free reseller platform with multiple free modules and are open source systems.

– Platforms based on asterisk, elastisk, trixbox, a2billing, unlicensed voipswitch servers with no cost and free modules. This looks like an advantage because the low price or even free in most of cases. However it brings high risks that become in disadvantages for the business. We suggest that you contact a company with plenty experience and get from them a kind of contract with SLA “Service Level Agreement”, support and warranty. You should NEVER buy or rent a “pirate” or “unlicensed” platform because you may be a victim of hacking and theft of your data, money and lose your reputation and customers.

Disadvantages for users with gray routes:

– Quality problems are frequent. Understand “poor quality” as a low value in ASR (Average Success Ratio) or in the Average Call Duration (ACD). In other words it is bad quality when you have to try the call many times to be able to complete a single call. Or the fact that you have to call several times because the call is cut frequently.

– It is probable that each call attempt will be charged from the moment it starts ringing (FAS).

– Limited channel capacity for simultaneous calls. It is very common that the terminator will sell the same channels to several customers and congestion or rejection of calls will occur. For users it can be frustrating to have to retry many times in order to speak.

– When the termination provider uses a poor internet connection, audio jams will occur during the call, and even one of the call legs can remain silently for several seconds (packet loss and no quality of service).

– Because the gray termination uses SIM cards (GSM) or traditional fixed analog lines, there is the need to redial or regenerate the call. This causes a long time at the beginning of the call to be able to connect to the destination, In technical terms a high Post Dial Delay (PDD).

– Some terminators that use GSM or VoIP-PSTN gateways install them in a rudimentary location or in “hidden” or “far” places; so the GSM signal is frequently chopped. This results in interference or low audio volume or noise.

– Gray terminators often use open source systems or unlicensed based telecommunications equipment. These are great risks against possible attacks or instability of the software, when the administrators do not have enough experience.

– Legal problems for the terminating company (in the country of termination) and possibly for the buyer. For example in some countries the mobile operators include in their contracts statements with prohibition for resale or termination or redirection or diversion of traffic.

– Due to the great competition in the gray voip market, it is very common that few people perform the administration, operation and maintenance tasks, to reduce personnel costs. So the end-users will see poor support, have to wait long time for answers or issues resolution.

– Due to ease and economy implementation of gray termination with SIM cards, new “voip provider companies” appears very often and also disappear within a few months suddently. This because mobile operators are blocking their SIM cards, IMEI equipment is reported. Also it is possible they fail to achieve customer loyalty due to continuous service failures. So those people prefer to create another new “voip company” with another logo and page and start bussines again. Unfortunately there are many dishonest people in this type of business who cheat with very low prices and then disappear with the money of their customers.

How to identify if I am using a gray route?

– Use the VOIP account to call to your cell phone, two or three times. If you see incoming calls from mobile numbers, then it is very possible thar SIM cards are being used for call termination or call-regeneration. If you see different calling numbers looks like fixed line identifier, then those call are being regenerated by using a gateway connected to regular phone lines. In these cases you are using gray routes!

In the other hand, if the caller identifier always showes the voip account login number or a DID phone number or an extension number, then GOOD NEWS! You ARE NOT using gray routes!

DIRECT Routes:

A DIRECT voip route is an interconnection between telecommunications companies that allows you to complete calls with the highest audio quality and transmits the originating telephone number to the final destination (CLI).

The direct routes have a property that differentiates them from other routes or terminations: CLI.

CLI are the initials of “Calling Line Identification”. CLI represents the telephone number of the originating party (A). This can be a complete telephone number or a part thereof, depending on the carrier or telecommunications company. In communications originating from a voip account it is very common for the CLI direct route to display the login number of that voip account in the destination telephone set. If that voip account has an associated DID (phone number) the destination could receive that number as the origination calling party.

How to identify if a route is DIRECT?

When you get a VOIP account you always receive the data to configure your softphone or voip device like this:

– A login number or account ID

– The service password or password

– The IP address or domain name of the server of the voip provider.

Set up your voip device and make a call to your mobile phone. Look at the caller ID which phone number appears as a caller. If you look at the login number or account ID in the identifier, that voip provider used a direct route with CLI. If you see another very different number that route is NOT direct with CLI.

WHITE route:

Some voip providers use the term “white route” to imply that it is not “gray route” and that route is better. However, this term only confuses the user. This confusion happens when the customer discovers that provider is selling GSM termination with SIM cards with the name of “white route”. The voip providers explain or defend themselves by stating that their termination use SIM Cards but that it is “legal” and that’s why they call it “white route”.

A “white” route may be legal or not, but it will have the same disadvantages or disadvantages of any GSM termination with SIM Cards or analog lines as explained above in the “gray route” section.

A responsible voip provider should say that their white route has CLI or it is a direct route with CLI. In this way the customer would fully understand there is not a GSM termination and they are really offering a high quality termination.

The discussion of legality or illegality of the routes is not part of the purpose of this entry. It will be an issue that should be considered by the user and supplier at its discretion. But we want to create discussion about the technical subject and characteristics that allow to identify each type of route between those offered in the market right now.

Conclusion: If a voip provider offers you “white route”; Could you ask if that “white route” has CLI or not? That will technically clarify what type of route you are buying.

GSM Route:

GSM route is a route that ends traffic using cellular mobile lines (SIM Cards). These SIM cards are installed on GSM gateway devices and allow the simultaneous termination of N calls depending on the number of channels of the equipment installed for this purpose.

GSM routes are actually “gray routes” unless the provider guarantees that it has a formal and explicit permission (contract document), by the destination mobile telecommunications company, to allow it to resell and terminate voip traffic using mobile lines. This type of contract does not exist at the level of networks interconnections unless it is a very special implementation where direct interconnection is not possible or when there is a formal permit to completing calls by a company by using their SIM cards as part of a corporate plan (exclusive use for that company) .

In the market there are very robust telecommunications equipment that allows to control and finish traffic with SIM cards offering high audio quality and good traffic statistics. This allows a GSM termination with acceptable quality. These devices minimize the risks explained in the “gray routes” section regarding the technical side but legal risks remain latent when the mobile telephone operator coul block SIM cards or blocks because unauthorized use of those lines and equipment (IMEI).

Unfortunately few vendors invest in robust equipment for GSM termination and high capacity for internet connection, and redundancy in their infrastructure. These equipments are expensive and also require special technical training for administration. Therefore, the selling price of those minutes is raised towards the end user. There are much cheaper equipment on the market that makes GSM termination too, but they bring a lot of quality complications in calls and the system administration is kind of tricky.


Route “PREMIUM” is a mixture of routes that group the best terminations available in each country.

Because no termination from VoIP to PSTN is allowed in all countries, through direct interconnection with central offices, PREMIUM routes have direct routes with CLI for some countries and GSM, or indirect routes, for countries with difficult access or with extreme restrictions for voip.

Every voip user has different needs in terms of pricing and quality. Ask your provider if they have direct CLI routes for those destinations where you require high quality. If not possible to get that answer, please ask for a free trial to use the best quality termination they can offer. So you could make tests and so would not have any surprises.

It is very common that providers of CLI direct routes and premium routes, provide to you, without additional cost, consultancy and technical support in case you find any quality problem in the calls or by using their management platform.


Some voip providers use the term “standard route” to imply that they are economic routes for those who give more importance to price than quality. This term is quite subjective and confuses the users. This term “standard route” is not clear about what quality is being offered and what are the statistics for those routes.

These types of routes change their price and quality very often and make a retail or corporate customer very frustrated and confused. We suggest this kind of routes when you have your own server or system that allow to change the routing on front of provider´s changes which affect your end users.


We suggest you always buy DIRECT CLI or PREMIUM routes if you are looking for quality rather than low price. You will not be worried about quality of service or audio issues or billing mismatches. Your phone system will work smootly.

If you are willing to sacrifice quality for a low price, look for suppliers of GRAY or GSM routes. But make sure to have more providers for redundancy and keep an eye on the system statistics in order to fix any error or re-route the trafic quickly. Contract a technical people to take care about these operations and maintennance tasks.


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