Tài liệu Thực hiện tiếng nói qua IP (P4) pptx

... 4 CRITERIA FOR EVALUATING VoIP SERVICE1 In this chapter, I describe a set of important criteria that can be used to per- form qualitative and quantitative measurements of IP phone or POTS phone (black ... voice packets; (c) use multiple moderate- speed WAN IP links for VoIP applications, and periodically monitor the utili- zation of these links in order to route the VoIP calls and tra‰c i...

Ngày tải lên: 15/12/2013, 05:16

... o¤ered over an IP network. The resulting architecture demands VoIP GWs to convert the TDM-formatted voice signal into IP packets at the ingress and vice versa at the egress. The VoIP GK controls ... international o‰ces, VoIP implementation may be preferable because such corporations may already have a large operational IP or overlay -IP network in place. The addition of VoIP service in...

Ngày tải lên: 15/12/2013, 05:16

... congestion in the network. Even though IPv4 is the most widely used version of IP in the world, the IETF is already developing the next generation of IP (IPv6, RFC 1883; the header format is shown ... legacy VoIP protocol. Figure 2-7 shows the protocol layers for real-time services like VoIP using the H.323 protocol. Other emerging VoIP protocols are IETF’s session initiation protocol (SI...

Ngày tải lên: 15/12/2013, 05:16

... as well. The following variants of SIP have emerged during the past few years: SIP-, SIP best common practice (SIP-BCP), SIPþ/SIP-T, and so on. However, SIPþ/SIP-T appears to be the most useful ... and hardware-based SIP and IP phones were available. For call routing over a large IP network, SIP may use the TRIP (telephony routing over IP, a work-in-progress in IETF’s IPTel WG, RFC 2871)...

Ngày tải lên: 15/12/2013, 05:16

... Without proper synchronization of the asynchronously operating IP- PSTN GWs and other IP domain network elements like routers and SIP or IP phones, voice quality and service reliability cannot be assured. The ... and IP networks, IP network impairments, and ele- ments of SS7 networks like SCP and STP. Other network elements include (a) the network timing server, (b) software- and har...

Ngày tải lên: 15/12/2013, 05:16

... IP phones to high-end residential and enterprise markets. IP- PBX, IP CENTREX, AND IP- BASED PBX TIE LINES IP- PBXs are PBX devices that support the following: a. Various IP telephony and/or VoIP ... Expected from IP- PBX and IP- Centrex Simultaneous support of IP and POTS (analog, digital, ISDN-BRI) phones Support of VoIP for both ac- cess (IP phones) and trans- port (inter-PBX...

Ngày tải lên: 15/12/2013, 05:16

... di¤erent sets of IP addresses to guarantee the required quality of service; and d. Deployment of IP version 6 (IPv6, IETF’s RFC 2460/1883) or IP version 4 (IPv4, IETF’s RFC 791) with IPSec infrastructure ... networks. 94 VoIP IN THE PUBLIC NETWORKS an adjacent IP telephony GW, along with a VoIP call controller, must be added. The VoIP GW and the CC are interconnected to the same LAN t...

Ngày tải lên: 15/12/2013, 05:16

... NETWORKS 119 the VoIP or IP- telephony service within a corporation are IP- PSTN MGWs or VoIP GWs, VoIP call servers or call managers, IP phones, an uninterrupted power supply (UPS), and Ethernet and IP switches ... using IP- based network. The IP- PSTN MGWs of Figure 3-8 are now replaced by the IP- PBXs. The VoIP GW and CC (Fig. 8-2) control the resources in the VoIP line cards of t...

Ngày tải lên: 15/12/2013, 05:16

... on. GUIDELINES FOR IMPLEMENTING VoIP 129 SIP-based VoIP service can be introduced in any operational IP network of an enterprise by deploying the SIP server-based VoIP call controller (CC), call manager, ... of plug-and-talk-based IP phones. These phones can support VoIP service over IP- based networks equipped with a call controller (CC) and MGW. As discussed in Chapter 6, IP phones c...

Ngày tải lên: 24/12/2013, 13:16

... cho bạn từng bước hoặc tự động thưc hiện toàn bộ cho bạn. Các hoạt động Guided Help thực hiện có thể được gỡ bỏ sau khi Guided Help kết thúc. Muốn thực hiện lại, bạn khởi động Guided Help ... booting". Bài này mô tả cách thực hiện clean boot, cách khởi động dịch vụ Windows Installer và cách phục hồi máy tính sau khi clean boot như thế nào. Chú ý: Sau khi thực hiện...

Ngày tải lên: 26/01/2014, 04:20