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9 votes
Accepted

Is QoS an issue for VOIP calls over the Internet? If not, why not?

VoIP over the public Internet can be a problem, but it usually works good enough, most of the time, although there can be times where it sucks. Most ISPs have extra cost features where they will honor ...
Ron Maupin's user avatar
  • 99.9k
8 votes

Is QoS an issue for VOIP calls over the Internet? If not, why not?

I'm trying to decide whether I should buy SIP trunks from my ISP or a 3rd-party. and... Is QoS an issue for VOIP calls over the Internet? Short answer: End-to-end QoS is NOT offered on the public ...
Mike Pennington's user avatar
7 votes
Accepted

Is TCP slow start supposed to be enabled for VoIP SIP?

Should TCP slow start be used with SIP-over-TCP? SIP does not transfer large data with TCP. SIP is only used for signaling, the transport of the actual data (voice, video, ...) is done with RTP and ...
Steffen Ullrich's user avatar
6 votes

Cisco 3750 - configure to mimic multi location scenario

First, you should probably not use VLAN 1 - it's generally not recommended, or if used, used for network device management traffic only. But, to answer your question, yes, you'd be using inter-vlan ...
Michael D's user avatar
5 votes
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Is there a point to have VLANs if each PC client can access them all?

By themselves, VLANs do not offer any security. But you use them to implement layer 3 security. Remember that VLANs are layer 2 concepts, while IP subnets are layer 3 concepts. In most cases, there ...
Ron Trunk's user avatar
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5 votes

VLAN Tags Being Different for a VoIP Phone vs. the Host Daisy-Chained to it?

Certainly this is the usual situation for the Cisco and Avaya phones I'm familiar with, as it's usual to keep voice and data traffic separate. This is from a Cisco SPA504G phone web configuration; ...
jonathanjo's user avatar
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5 votes

VLAN Tags Being Different for a VoIP Phone vs. the Host Daisy-Chained to it?

A VoIP phone that chains to another device is a switch, and it negotiates a trunk between the phone and the switch. This happens with CDP or LLDP. For example, a Cisco switch interface configured as ...
Ron Maupin's user avatar
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4 votes

Can I run two separate internet connections over one Cat5e cable

Yes it is possible all you need is a router where both links will get terminated for voice and data it would act as an gateway. Then you need switch connected via router in switch there would be 2 ...
Deepak Singh's user avatar
4 votes
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VoIP only for two phones

Yes. You can connect 2 IP phones same network (LAN and it should not be exposed to the internet because you'll get ghost calls) and call the other phone by dialing its local IP address, even when the ...
Yisroel Tech's user avatar
4 votes
Accepted

Is an SBC sufficient and can it NAT

From what I understood about SBCs (by virtue of providing the networks, firewalls and routing for SBC deployments), an SBC does not (need to) actually route/forward IP packets between customer and SP ...
Marc 'netztier' Luethi's user avatar
4 votes
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VLAN VoIP and LAN configuration over multiple switches

If all your connections between switches are layer 2, then yes, you need to trunk all VLANs across your backbone switch. The ports connecting your switches to the backbone will be configured as ...
Ron Trunk's user avatar
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4 votes

Whats the difference between VOICE VLAN and ACCESS VLAN

The access VLAN is what is used for devices, such as PCs, connecting to the switch interface. VoIP phones can use CDP (or possibly LLDP, depending on the model and switch configuration) to negotiate ...
Ron Maupin's user avatar
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4 votes
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Whats the difference between VOICE VLAN and ACCESS VLAN

Traditionally with Switching, there are two types of ports: Access Ports -- ports which carry traffic for only one VLAN Trunk Ports -- ports which carry traffic for multiple VLANs In a scenario ...
Eddie's user avatar
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3 votes
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Mostly wireless campus vs. VoIP

While wireless is a good, convenient, possibly necessary thing for a company to have and use, you don't own the airwaves, and you must be willing to accept any interference that disrupts your Wi-Fi, ...
Ron Maupin's user avatar
  • 99.9k
3 votes

VoIP on a remote VPN site

They can be on the same VLAN. That will have no impact whatsoever. Your main potential issue is the lack of QoS on the Internet path. Interestingly, this is a special scenario where disabling split ...
Ronnie Royston's user avatar
3 votes

Understanding of NAT and VoIP

If peer "B" sends a request first to start a session then no STUN/TURN is required in your case because the request will be directly forward to peer "A" by DMZ server and it won't be blocked by NAT ...
defalt's user avatar
  • 400
3 votes

How does "dual-line" feature work on Cisco/Avaya IP phones for VOIP?

If the huntstop attribute is set, an incoming call does not roll over (hunt) to another ephone-dn when the called ephone-dn is busy or does not answer and a hunting strategy has been established that ...
MUSR's user avatar
  • 536
3 votes
Accepted

Phone and PC network sharing one wifi bridge

It will work. Keep in mind this to learn why: 1 - A LAN is a single broadcast domain and single collision domain. Collision Domain: It means that a collision will be sensed by all the devices in the ...
jcbermu's user avatar
  • 4,497
3 votes

Advice on potentially needed subnet expansions

The lack of VLANs probably also means the lack of QoS. In that case you may find you get poor voice quality and your project may not be successful. You really need to upgrade your hardware. But to ...
Ron Trunk's user avatar
  • 67.7k
3 votes

ISP Failover On A Converged Network

Depending on how your network is set up, this is certainly possible. You can configure the phones to pass VoIP on a dedicated, tagged VLAN and traffic from the internal switch untagged - this is what ...
Zac67's user avatar
  • 85.5k
3 votes
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Landline phone on VOIP network without an adapter

No. VoIP over Ethernet is so vastly different from POTS that it's absolutely impossible to connect without a SIP gateway (which might come as an "Ethernet to telephone adapter" but it requires power ...
Zac67's user avatar
  • 85.5k
3 votes
Accepted

qos inside vpn, possible or not ? I read yes and no

Possible? Generally, yes. However, you need to consider the tunnel outside as well. How effective QoS works depends on a large number of parameters only some of which you have control over. QoS ...
Zac67's user avatar
  • 85.5k
3 votes
Accepted

How does UDP provide continuous sound in VOIP even though segments are discrete?

The audio data is "time-compressed" when transmitted. Imagine a 800 byte UDP datagram carrying 8 kHz 8-bit VoIP data. The 800 samples cover 1/10th of a second (or 100 ms) when played back. That ...
Zac67's user avatar
  • 85.5k
2 votes

How is it possible to run VoIP on CAT3. Do you not need CAT5 for the voice data?

Allow me to clarify that It is possible to use cat3 cabling for IP phones in addition to POE. Since the early 1990s, prior to many IP standards and written documentation for LAN Networks I have ...
Mark Fratarcangeli's user avatar
2 votes

Which header is added to the voice data payload in Layer-2 when we use an IPsec VPN?

That is official documentation from Cisco, so I don't doubt that. As far as L2 header is concerned it is added depending on the L2 technology(Ethernet, Frame Relay etc.) The document is not taking L2 ...
MUSR's user avatar
  • 536
2 votes

Call incoming from PSTN does not forward to cellphone number

Mr.Cebollin, I had the same issue and this is because the E1 Service Provider will not allow it as a restriction to avoid Toll-Fraud. In my case to make it work, I used the highlighted option. Hope ...
Vignesh Sethuraman's user avatar
2 votes

How do I diagnose a VoIP issue on a Cisco 2811?

for me it sounds like problem in CALL HUNTING configuration you have two ephone-dn 's (4 & 22) with 2000 extension ,which will handle the incommoding calls, where 4 with preference 0 and 22 with ...
Gadeliow's user avatar
  • 3,444
2 votes

Smart switching calls in a company phone calls

Typically in order to handle this type of scenario, you need to add an ACD (Automatic Call Distribution) component to your telephony solution, and tie it into your CRM. The idea is that your CRM tool ...
Jeremy Gibbons's user avatar

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