Choosing a VoIP Voice Gateway
Everyone who came across IP telephony must have come across the choice of a VoIP gateway for connecting an IP-PBX to a telephone network, to an existing PBX, an analog telephone, and so on. When choosing a VoIP gateway, the question always arises - which gateway to choose and how they differ from each other. Actually, I wanted to talk about this in this article - how one gateway differs from another and what you should pay attention to when choosing. Naturally, I can’t give a final recipe on which gateway I’d like to buy, since ultimately any choice consists of a number of factors: requirements, desires and price. Here I want to describe the main features that are worth paying attention to, and you will need to decide for yourself what is more important for you. So, let's begin:
Today, more and more companies are using IP telephony and Unified Communications. In turn, manufacturers also do not stand still and offer more and more IP telephony solutions. But do not forget that the very SIP that is not being talked about now, except that the lazy one is not one standard, but a set of recommendations, where RFC 3261 is just a small part. When one or another manufacturer writes that it supports transferring a call or holding a call, this does not mean that this service will work specifically with your IP-PBX. For example, your PBX supports the call transfer method according to RFC 3892 (REFERED-BY), and the gateway supports the method according to RFC 3515 (REFER). On the one hand, both options work according to the standard (more precisely, recommendations), but in the end they are not compatible with each other. Moreover, there is no one to complain. In this regard, it is always required to check not the set of functionality that is available on a particular VoIP gateway, but the set of standards that the gateway supports. And so that equipment manufacturers do not say that everything is compatible and SIP is unified - in practice this is not so, since each manufacturer strives to create his own unique service. And this leads to the fact that manufacturers create their own standards and these standards become only larger and the compatibility problem does not become easier. Because of this, when buying a VoIP gateway, it is better to check on the site manufacturer’s website what gateways your IP-PBX works with and what are the restrictions. Separately, we can mention the support for the H.323 protocol, which is still in use. I will not go into H.323 compatibility in this article, since the protocol is no longer being developed and no manufacturer is developing it, it only supports it. There is also compatibility from TDM. It would seem that TDM and analog telephony are standardized so that there should not be compatibility problems, but in practice there are a lot of questions, starting with support for pulse dialing (and stations that do not support tone dialing still exist in large numbers, not to mention already about phones), the correct determination of tones in the line and ending with various fields of ISDN. But this topic also should not be stopped, as practice shows, those people who have such problems take what they were able to get to work on tests and themselves know about these problems. There is also compatibility from TDM. It would seem that TDM and analog telephony are standardized so that there should not be compatibility problems, but in practice there are a lot of questions, starting with support for pulse dialing (and stations that do not support tone dialing still exist in large numbers, not to mention already about phones), the correct determination of tones in the line and ending with various fields of ISDN. But this topic also should not be stopped, as practice shows, those people who have such problems take what they were able to get to work on tests and themselves know about these problems. There is also compatibility from TDM. It would seem that TDM and analog telephony are standardized so that there should not be compatibility problems, but in practice there are a lot of questions, starting with support for pulse dialing (and stations that do not support tone dialing still exist in large numbers, not to mention already about phones), the correct determination of tones in the line and ending with various fields of ISDN. But this topic also should not be stopped, as practice shows, those people who have such problems take what they were able to get to work on tests and themselves know about these problems. which do not support tone dialing still exist in large numbers, not to mention phones), the correct definition of tones in the line and ending with various ISDN fields. But this topic also should not be stopped, as practice shows, those people who have such problems take what they were able to get to work on tests and themselves know about these problems. which do not support tone dialing still exist in large numbers, not to mention phones), the correct definition of tones in the line and ending with various ISDN fields. But this topic also should not be stopped, as practice shows, those people who have such problems take what they were able to get to work on tests and themselves know about these problems.
A VoIP gateway is an infrastructure device, and its feature is a physical limitation in performance. If data networks grow and more and more productive equipment appears that supports 100 Mbps, 1000 Mbps, 1 Gbps, and so on. In telephony, one line with one simultaneous connection is connected via one analog port, the E1 stream has 31 time slots and supports 30 or 31 simultaneous connections, depending on the type of signaling. This has not changed for many years and will never change. On the other hand, there is VoIP, where everything changes quickly and dynamically - a new IP-PBX appears, new services and standards appear, unified communications come and so on. If with network equipment, when new services appear, you usually There is no question why more bandwidth of your IP channel is required and according to this you change routers / switches. That is why when changing the IP-PBX or just updating the IP-PBX you need to change the VoIP gateway is not clear. After all, you do not change the type of connection to the telephone network and the IP-PBX still supports SIP. But it turns out that the manufacturer of the VoIP gateway removed your model from production and created a new model and does not support the old one. Moreover, sometimes the life of the model can be 1-2 years, which is negligible for such a conservative world as telephony. I agree that the equipment is becoming obsolete, production technologies are changing, but for me the period of support for a VoIP gateway is a very important factor. That is why when changing the IP-PBX or just updating the IP-PBX you need to change the VoIP gateway is not clear. After all, you do not change the type of connection to the telephone network and the IP-PBX still supports SIP. But it turns out that the manufacturer of the VoIP gateway removed your model from production and created a new model and does not support the old one. Moreover, sometimes the life of the model can be 1-2 years, which is negligible for such a conservative world as telephony. I agree that the equipment is becoming obsolete, production technologies are changing, but for me the period of support for a VoIP gateway is a very important factor. That is why when changing the IP-PBX or just updating the IP-PBX you need to change the VoIP gateway is not clear. After all, you do not change the type of connection to the telephone network and the IP-PBX still supports SIP. But it turns out that the manufacturer of the VoIP gateway removed your model from production and created a new model and does not support the old one. Moreover, sometimes the life of the model can be 1-2 years, which is negligible for such a conservative world as telephony. I agree that the equipment is becoming obsolete, production technologies are changing, but for me the period of support for a VoIP gateway is a very important factor. that the manufacturer of the VoIP gateway removed your model from production and created a new model and does not support the old one. Moreover, sometimes the life of the model can be 1-2 years, which is negligible for such a conservative world as telephony. I agree that the equipment is becoming obsolete, production technologies are changing, but for me the period of support for a VoIP gateway is a very important factor. that the manufacturer of the VoIP gateway removed your model from production and created a new model and does not support the old one. Moreover, sometimes the life of the model can be 1-2 years, which is negligible for such a conservative world as telephony. I agree that the equipment is becoming obsolete, production technologies are changing, but for me the period of support for a VoIP gateway is a very important factor.
It is rather a requirement for analog gateways with FXS ports. One of the advantages of IP telephony is that the VoIP gateway can be placed as close as possible to the telephone installation site. But the closer the equipment to the installation site, the higher installation requirements:
Probably, each of us was faced with the problem that the build quality or the quality of plastic from particularly cheap manufacturers leaves much to be desired. But if the build quality can simply lead to the fact that somewhere you can unscrew the screw or break the ports when pulling out the cables (naturally random). That quality of plastic, which people like to save on, can turn out worse. As I wrote earlier, cooling is quite an important factor in a VoIP gateway, and if the quality of plastic is good or a steel case is used, then only the device will break when the device burns out. But if the quality of the plastic leaves much to be desired, then in addition to what it can smell during operation, what it can do when writing a fan breakdown, I think, is not worth it. And given the fact that the equipment is not in the server,
Returning to the topic that the installation site of equipment may be different, the requirements for remote management and monitoring are increasing. And if manufacturers of small devices seek to support TR-069, to control the telecom operator. That is, for installation in the infrastructure of the enterprise always requires SNMP, and even better the ability to console cable.
This is probably the factor that is very important, but which everyone does not pay attention to when choosing, but only during operation. When a gateway is tested, it usually passes under "sterile" conditions. When the gateway is installed on the network, it turns out that the quality is not as we would like - there is an echo, unnecessary noise, faxes do not go (although T38 is supported and faxes were checked). And the reason, as a rule, is not that the wrong codec is used or the telephone has changed, the reason lies in the gateway itself and its DSP processor. Actually, how good is that DSP processor and its code that can convert the RTP stream that comes from the IP side, with all the problems of delays, jitter, losses, to the analog or digital signal of the synchronous stream and vice versa, the voice quality will depend. Same, a very important factor is the function of noise reduction, echo cancellation, signal strength control, pause detection and other purely voice, telephone functions. If earlier this functionality was completely assigned to the telephone exchange and all this was done in one place, now it is all done on VoIP terminal devices. And the quality of the voice in your VoIP network will greatly depend on the quality of the DSP. This parameter is rather subjective when choosing, but in practice, users feel it very objectively. And the quality of the voice in your VoIP network will greatly depend on the quality of the DSP. This parameter is rather subjective when choosing, but in practice, users feel it very objectively. And the quality of the voice in your VoIP network will greatly depend on the quality of the DSP. This parameter is rather subjective when choosing, but in practice, users feel it very objectively.
As well as IP-PBX manufacturers, manufacturers of VoIP gateways seek to provide their users with additional services. Here you can write for a long time about the services that this or that manufacturer provides, but of course I will not do this. I can only say that I advise you to pay attention to these services when choosing a gateway, since they can be very interesting for your infrastructure and will give you something that no other manufacturer will give. Who knows, maybe this is what will ultimately become the most important plus for you.
From the foregoing, I would like to add that you should not consider the price and availability of the basic call as the main criterion, but pay more attention to the little things. They make the quality product truly high-quality. And it turns out, like many operators, the cost of services falls more slowly than the quality of these same services.
1. Compatibility
Today, more and more companies are using IP telephony and Unified Communications. In turn, manufacturers also do not stand still and offer more and more IP telephony solutions. But do not forget that the very SIP that is not being talked about now, except that the lazy one is not one standard, but a set of recommendations, where RFC 3261 is just a small part. When one or another manufacturer writes that it supports transferring a call or holding a call, this does not mean that this service will work specifically with your IP-PBX. For example, your PBX supports the call transfer method according to RFC 3892 (REFERED-BY), and the gateway supports the method according to RFC 3515 (REFER). On the one hand, both options work according to the standard (more precisely, recommendations), but in the end they are not compatible with each other. Moreover, there is no one to complain. In this regard, it is always required to check not the set of functionality that is available on a particular VoIP gateway, but the set of standards that the gateway supports. And so that equipment manufacturers do not say that everything is compatible and SIP is unified - in practice this is not so, since each manufacturer strives to create his own unique service. And this leads to the fact that manufacturers create their own standards and these standards become only larger and the compatibility problem does not become easier. Because of this, when buying a VoIP gateway, it is better to check on the site manufacturer’s website what gateways your IP-PBX works with and what are the restrictions. Separately, we can mention the support for the H.323 protocol, which is still in use. I will not go into H.323 compatibility in this article, since the protocol is no longer being developed and no manufacturer is developing it, it only supports it. There is also compatibility from TDM. It would seem that TDM and analog telephony are standardized so that there should not be compatibility problems, but in practice there are a lot of questions, starting with support for pulse dialing (and stations that do not support tone dialing still exist in large numbers, not to mention already about phones), the correct determination of tones in the line and ending with various fields of ISDN. But this topic also should not be stopped, as practice shows, those people who have such problems take what they were able to get to work on tests and themselves know about these problems. There is also compatibility from TDM. It would seem that TDM and analog telephony are standardized so that there should not be compatibility problems, but in practice there are a lot of questions, starting with support for pulse dialing (and stations that do not support tone dialing still exist in large numbers, not to mention already about phones), the correct determination of tones in the line and ending with various fields of ISDN. But this topic also should not be stopped, as practice shows, those people who have such problems take what they were able to get to work on tests and themselves know about these problems. There is also compatibility from TDM. It would seem that TDM and analog telephony are standardized so that there should not be compatibility problems, but in practice there are a lot of questions, starting with support for pulse dialing (and stations that do not support tone dialing still exist in large numbers, not to mention already about phones), the correct determination of tones in the line and ending with various fields of ISDN. But this topic also should not be stopped, as practice shows, those people who have such problems take what they were able to get to work on tests and themselves know about these problems. which do not support tone dialing still exist in large numbers, not to mention phones), the correct definition of tones in the line and ending with various ISDN fields. But this topic also should not be stopped, as practice shows, those people who have such problems take what they were able to get to work on tests and themselves know about these problems. which do not support tone dialing still exist in large numbers, not to mention phones), the correct definition of tones in the line and ending with various ISDN fields. But this topic also should not be stopped, as practice shows, those people who have such problems take what they were able to get to work on tests and themselves know about these problems.
2. Duration of support
A VoIP gateway is an infrastructure device, and its feature is a physical limitation in performance. If data networks grow and more and more productive equipment appears that supports 100 Mbps, 1000 Mbps, 1 Gbps, and so on. In telephony, one line with one simultaneous connection is connected via one analog port, the E1 stream has 31 time slots and supports 30 or 31 simultaneous connections, depending on the type of signaling. This has not changed for many years and will never change. On the other hand, there is VoIP, where everything changes quickly and dynamically - a new IP-PBX appears, new services and standards appear, unified communications come and so on. If with network equipment, when new services appear, you usually There is no question why more bandwidth of your IP channel is required and according to this you change routers / switches. That is why when changing the IP-PBX or just updating the IP-PBX you need to change the VoIP gateway is not clear. After all, you do not change the type of connection to the telephone network and the IP-PBX still supports SIP. But it turns out that the manufacturer of the VoIP gateway removed your model from production and created a new model and does not support the old one. Moreover, sometimes the life of the model can be 1-2 years, which is negligible for such a conservative world as telephony. I agree that the equipment is becoming obsolete, production technologies are changing, but for me the period of support for a VoIP gateway is a very important factor. That is why when changing the IP-PBX or just updating the IP-PBX you need to change the VoIP gateway is not clear. After all, you do not change the type of connection to the telephone network and the IP-PBX still supports SIP. But it turns out that the manufacturer of the VoIP gateway removed your model from production and created a new model and does not support the old one. Moreover, sometimes the life of the model can be 1-2 years, which is negligible for such a conservative world as telephony. I agree that the equipment is becoming obsolete, production technologies are changing, but for me the period of support for a VoIP gateway is a very important factor. That is why when changing the IP-PBX or just updating the IP-PBX you need to change the VoIP gateway is not clear. After all, you do not change the type of connection to the telephone network and the IP-PBX still supports SIP. But it turns out that the manufacturer of the VoIP gateway removed your model from production and created a new model and does not support the old one. Moreover, sometimes the life of the model can be 1-2 years, which is negligible for such a conservative world as telephony. I agree that the equipment is becoming obsolete, production technologies are changing, but for me the period of support for a VoIP gateway is a very important factor. that the manufacturer of the VoIP gateway removed your model from production and created a new model and does not support the old one. Moreover, sometimes the life of the model can be 1-2 years, which is negligible for such a conservative world as telephony. I agree that the equipment is becoming obsolete, production technologies are changing, but for me the period of support for a VoIP gateway is a very important factor. that the manufacturer of the VoIP gateway removed your model from production and created a new model and does not support the old one. Moreover, sometimes the life of the model can be 1-2 years, which is negligible for such a conservative world as telephony. I agree that the equipment is becoming obsolete, production technologies are changing, but for me the period of support for a VoIP gateway is a very important factor.
3. Installation requirements and type of cooling
It is rather a requirement for analog gateways with FXS ports. One of the advantages of IP telephony is that the VoIP gateway can be placed as close as possible to the telephone installation site. But the closer the equipment to the installation site, the higher installation requirements:
- Passive cooling: probably no one likes when a fan rustles under his ear. But this is not the only problem. You will not check the fan operation every day, and support for remote monitoring of the fan on such models is usually not provided, and if the fan breaks down, the gateway itself will break quickly enough. Moreover, this will not be a warranty case. You need to understand that a gateway with FXS ports requires electricity for each port, and this makes the technical solution for cooling, with increasing ports, only more difficult.
- Work environment: Naturally, the gateway in this case is not in the server room, and you cannot control the temperatures that are in the room. From here it is important to also look at those operating temperatures that the manufacturer indicates more closely.
4. Build quality
Probably, each of us was faced with the problem that the build quality or the quality of plastic from particularly cheap manufacturers leaves much to be desired. But if the build quality can simply lead to the fact that somewhere you can unscrew the screw or break the ports when pulling out the cables (naturally random). That quality of plastic, which people like to save on, can turn out worse. As I wrote earlier, cooling is quite an important factor in a VoIP gateway, and if the quality of plastic is good or a steel case is used, then only the device will break when the device burns out. But if the quality of the plastic leaves much to be desired, then in addition to what it can smell during operation, what it can do when writing a fan breakdown, I think, is not worth it. And given the fact that the equipment is not in the server,
5. Management and monitoring
Returning to the topic that the installation site of equipment may be different, the requirements for remote management and monitoring are increasing. And if manufacturers of small devices seek to support TR-069, to control the telecom operator. That is, for installation in the infrastructure of the enterprise always requires SNMP, and even better the ability to console cable.
6. DSP
This is probably the factor that is very important, but which everyone does not pay attention to when choosing, but only during operation. When a gateway is tested, it usually passes under "sterile" conditions. When the gateway is installed on the network, it turns out that the quality is not as we would like - there is an echo, unnecessary noise, faxes do not go (although T38 is supported and faxes were checked). And the reason, as a rule, is not that the wrong codec is used or the telephone has changed, the reason lies in the gateway itself and its DSP processor. Actually, how good is that DSP processor and its code that can convert the RTP stream that comes from the IP side, with all the problems of delays, jitter, losses, to the analog or digital signal of the synchronous stream and vice versa, the voice quality will depend. Same, a very important factor is the function of noise reduction, echo cancellation, signal strength control, pause detection and other purely voice, telephone functions. If earlier this functionality was completely assigned to the telephone exchange and all this was done in one place, now it is all done on VoIP terminal devices. And the quality of the voice in your VoIP network will greatly depend on the quality of the DSP. This parameter is rather subjective when choosing, but in practice, users feel it very objectively. And the quality of the voice in your VoIP network will greatly depend on the quality of the DSP. This parameter is rather subjective when choosing, but in practice, users feel it very objectively. And the quality of the voice in your VoIP network will greatly depend on the quality of the DSP. This parameter is rather subjective when choosing, but in practice, users feel it very objectively.
7. Additional features
As well as IP-PBX manufacturers, manufacturers of VoIP gateways seek to provide their users with additional services. Here you can write for a long time about the services that this or that manufacturer provides, but of course I will not do this. I can only say that I advise you to pay attention to these services when choosing a gateway, since they can be very interesting for your infrastructure and will give you something that no other manufacturer will give. Who knows, maybe this is what will ultimately become the most important plus for you.
From the foregoing, I would like to add that you should not consider the price and availability of the basic call as the main criterion, but pay more attention to the little things. They make the quality product truly high-quality. And it turns out, like many operators, the cost of services falls more slowly than the quality of these same services.