Telesis PX24 IP PBX Business Phone System
Design and manufacture IP PBX Business Phone System, Switching System, VoIP Gateway, and Signaling Converter  

Q&A for Telesis VoIP Technology

  • Q: What is a Hybrid IP PBX system?
  • A: A Hybrid IP PBX provides analog TDM, digital TDM, and VoIP capabilities at the same time. Consequently, it is possible to use a mixture of analog, digital, and IP based terminals like phones in the same system. Furthermore, a Hybrid IP PBX offers similar features and services to both TDM and IP users. Migrating to VoIP is easy and comfortable with using a Hybrid IP PBX system. Telesis PX24 systems are Hybrid IP PBXs for small to large business.


Telesis Hybrid IP PBX Business Phone Systems allow many connections

  • Q: What does the VoIP channel license mean for Telesis PX24 Hybrid IP PBX systems?
  • A: Telesis systems are with IP-TDM Gateway and media proxying capabilities. That means calls from the TDM network (circuit switched network) may be routed to the IP network and vice versa. Also, whenever it is necessary the integrated media proxy operates for calls between VoIP entities (like in H.323 and SIP integration). VoIP channel license in Telesis systems refers to the allowed simultaneous calls from TDM to IP (SIP or H.323) and IP (SIP or H.323) to TDM network, as well as half of the simultaneous calls made by using the integrated media proxy. To illustrate, in order to have a capacity of 8 simultaneous calls from the IP network to the TDM one, a Telesis system must have been licensed with minimum 8 VoIP-TDM gateway channels. To remind you, whenever a licensed channel is free, it can be used by any TDM or VoIP user. Note that, VoIP calls here refer to SIP or H.323 VoIP calls only. VoIP calls with using Telesis xSIP protocol are excluded.
  • Q: How many VoIP-TDM gateway channels are available in Telesis PX24 Hybrid IP PBX systems?
  • A: The hardware of the PX24 Hybrid IP PBX systems is designed for 64 VoIP-TDM gateway channels at maximum. However, depending on the model and type of the system, the number of gateway channels for concurrent calls may be less than this number. To remind you, VoIP-TDM gateway channel licensing is in multiples of two. License your system according to your configuration and requirements. Especially, you should evaluate the call  traffic between TDM and IP users. Considering the capacities of the systems, we assume that much less than a dozen of VoIP-TDM gateway channel licenses may be sufficient even at high traffic. Please read the previous answer to understand what the VoIP-TDM gateway channel license means. Note that, VoIP calls here refer to SIP or H.323 VoIP calls only. VoIP calls with using Telesis xSIP protocol are excluded.
  • Q: I understand that the number of VoIP users in Telesis PX24M, and PX24X systems should be equal to the number of VoIP-TDM gateway channels. Is it correct?
  • A: No, it is wrong. The PX24M allows 160 VoIP entities (SIP or H.323) to be registered to its integrated gatekeeper or registrar. This maximum number of VoIP users increases to 512 in PX24X systems. Furthermore, equipping the systems with VoIP users is a standard feature even at basic configurations. In other words, this is free of charge. Some of these VoIP users (entities) may be IP trunk routes, i.e., remote getekeepers or registrars. Some others may be VoIP hard/soft phones with their own IP addresses. Note that, VoIP users here refer to SIP or H.323 VoIP users only. VoIP users with Telesis xSIP protocol are excluded.
  • Q: Can a Telesis PX24 Hybrid IP PBX register to an external H.323 gatekeeper or SIP registrar?
  • A: Yes. PX24M and PX24X systems support hundreds of VoIP entities, which can be local or remote users. This being the case, a PX24 system can register to multiple external gatekeepers and SIP registrars at the same time. Furthermore, the registration can be with or without authentication individually for each gatekeeper or registrar. This multiple registration capability results in a perfect flexibility for PX24 systems, especially while routing calls from TDM to IP network with LCR (Least Cost Routing), alternate routing. The multiple registration capability also provides redundancy in routing in an advanced and complicated VoIP network. 
  • Q: Assume that my PX24 Hybrid IP PBX system is licensed for 2 VoIP channels. How many VoIP phones I can connect to my system?
  • A: You may connect any number of VoIP phones independent of the available VoIP-TDM gateway channels in your system, provided that the total number of VoIP users is below the capacity allowed (i.e., maximum 160 users for the PX24M and 512 users for the PX24X). Any number of simultaneous but direct calls among the VoIP phones are possible. However, there can be maximum two (2) simultaneous calls from TDM network to these IP phones and vice versa with the license that you have. To remind you, whenever a licensed channel is free, it can be used by any TDM or VoIP user. Note that, VoIP users here refer to SIP or H.323 VoIP users only. VoIP users with Telesis xSIP protocol are excluded.
  • Q: Which protocols are supported in Telesis systems for VoIP calls?
  • A: Telesis systems support H.323, SIP and xSIP protocols for VoIP calls.
  • Q: What is xSIP?
  • A: xSIP stands for eXtended SIP protocol. It is developed by Telesis to make some value-added services in Telesis systems to be applicable for VoIP calls too.
  • Q: What are the user terminals with xSIP protocol?
  • A: Presently, Telesis offers two products. One is the ITS821 VoIP phone, and the other is the XPhone softphone. Both products bring the comfort of Telesis digital sets over IP. In other words, almost all the functions of Telesis digital telephones are also applicable over IP. To illustrate, ITS821 and XPhone are with a busy display panel showing the current status of 120 preprogrammed users in a Telesis Hybrid IPBX.
  • Q: Do I need VoIP-TDM gateway channel licenses  for xSIP-to-TDM or TDM-to-xSIP calls?
  • A: No, VoIP-TDM gateway channel licenses are reuired only for H.323 and SIP VoIP calls. xSIP protocol does not require VoIP-TDM gateway channel licenses for ITS821 (or XPhone) to TDM or TDM to ITS821 (or XPhone) call routing.  
  • Q: Do I need any other licenses to operate ITS821 or XPhone?
  • A: Each PX24M or PX24X supports a single xSIP user without requiring any licenses. Furthermore, XPhone is a freeware softphone. Consequently, you can easily test and see the capabilities of the XPhone without any cost. However, if you need more ITS821 or XPhone users then you will need to purchase necessary number of xSIP user licenses. 
  • Q: I am not able to access program menu in XCom and XPhone. How would I do this?
  • A: You may do it by pressing the right mouse key when its cursor is over the title bar.

  • Q: I understand that a PX24 Hybrid IP PBX systems also operate like a softswitch without needing any VoIP channel license. Am I right?
  • A: Yes, you are right. PX24 systems are also with the softswitch capability.
  • Q: Is it easy to install and operate Telesis PX24 Hybrid IP PBX systems in VoIP applications?
  • A: Yes, because the programming parameters for a VoIP application is easy with a WEB browser connection. People familiar to Telesis systems know how the integrated web server is user-friendly and easy-to-use. Furthermore, both H.323 and SIP protocols have been implemented according to the latest standards. However, some difficulties may appear depending on your application, external network equipment used, other IP equipment used, your internet service provider and your network experiences. These are not related to the PX24 systems and they common in IP Telephony applications. Furthermore, in order to make the installation smooth and easy, PX24 Hybrid IP PBX systems have been equipped with several adjustable parameters. Lastly, an online help system is also embedded into the integrated web server in order to assist system programmers.
  • Q: Assume that I have a Telesis PX24 Hybrid IP PBX at my office. Can I call to my office by using any PC and a softphone anywhere in the world?  
  • A: Yes, you can. In the PX24, it is possible to allow incoming calls from unregistered IP addresses. Such calls are named `visitor calls`. In the system, you may define a visitor profile and the PX24 may handle the calls from unregistered IP addresses according to the visitor profile defined. In general, the visitor profile may allow such calls to be terminated on the operator telephone. Consequently, anywhere and from any PC, you can access to the operator of your office PX24 with using a SIP or H.323 softphone.
  • Q: How does the integrated echo canceler operate in PX24 systems?
  • A: The echo canceler in PX24 systems is AT&T certified and according to G.168 standards. It meets and exceeds G.168-2002 requirements. It is better than industry standard cancelers under the most important and difficult conditions like double-talk and the presence of background noise. However, sometimes echo canceling is misunderstood. The truth is that it cancels the echo in the transmit direction. Assume that the PX24 is connected to another equipment over the IP. The echo canceler of the PX24 would make the user of the other connected equipment echo-free and comfortable while talking to the PX24 users. If the two PX24 systems would be interconnected over the IP then it is ensured that both side users would be in comfort while talking to each other.
  • Q: Can I connect to Telesis PX24 Hybrid IP PBX systems over the internet for maintenance and collect CMDR (call records) data?
  • A: Yes, you can. It is possible to access the PX24 from your LAN or from the public IP network. For maintenance, you will just need to use a PC with a web browser.  For collecting CMDR data, you will also need freeware XTools utility running on the PC. To prevent unauthorized accesses, you can program your PX24 system too. When you connect to the PX24 from the private network, the operation would be smooth and easy. While accessing the PX24 from the public IP network, you may also need some programming for the other network equipment like router, firewall.
  • Q: While bridging my distant offices over the IP by using Telesis PX24 Hybrid IP PBX systems, can I apply a common numbering plan?
  • A: Yes, you can. With the advanced routing and flexible numbering capabilities of the PX24 systems, it is very easy. In such private network, all the users may have a unique private telephone number. Each user can call to another without dialing a prefix digit, even without being aware that the called number residing in the same or in a distant office.
  • Q: Is it possible to see the calling party number on analog subscribers with Caller ID phones, Telesis digital phones or Basic Rate ISDN phones connected to the PX24 if the call comes from the IP network?
  • A: Yes, it is possible. If the VoIP signaling message has this information then the PX24 regenerates it accordingly while routing this VoIP call to the relevant analog, digital or ISDN subscriber telephone.
  • Q: I would like to generate billing records for VoIP calls based on the call duration. Is it possible to do it with the PX24?
  • A: Yes, it is possible. PX24 systems can be programmed to generate billing records for the VoIP calls based on the call duration and several other criteria like the called destination, date and time of the call, even the calling party number. To remind you, PX24 systems are very advanced in terms of routing and billing features making it an ideal choice for the telephone service providers too. The detailed call records with the charging information can be accessed with the freeware XTools utility.
  • Q: Does the media encryption operate among the Telesis systems only?
  • A: Yes. Telesis implementation for the media encryption aims secure VoIP calls among the Telesis systems while bridging the distant offices. We are not concerned about the interoperability with any other system. As we have said, our primary target is to make media encryption as secure as possible.
  • Q: If I license my PX24 system for media encryption, can I still place calls to some other VoIP entities (which are not Telesis ones)?
  • A: Yes. Having the media encryption license allows you to encrypt calls to a similarly configured and licensed Telesis system in a secure way. Media encryption may be activated or deactivated for selected routes through some simple programming. Consequently, you can still call some routes, which are non-Telesis systems by programming media encryption towards these routes. Of course, your Telesis system automatically decides on applying or not applying the media encrytion accordingly.

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