Questions tagged [sip]
For questions about the Session Initiation Protocol (SIP) typically used in VoIP and IP telephony.
37 questions
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Cisco CP-7841 IP Phone backlight settings not working [closed]
I have a couple of Cisco CP-7841 IP Phones that are working otherwise well, but the backlight controls are not working. I would like to have the backlight off unless the phone is being used (IIRC this ...
- 11
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1
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104
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Are SIP numbers provided by the SIP Trunk provider?
Background
I'm trying to understand how SIP works and the industry in general. We are planning to setup a PBX (open source) and have SIP phones for our customer care agents.
When I was researching on ...
5
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1
answer
393
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Is TCP slow start supposed to be enabled for VoIP SIP?
TCP slow start mechanism generally is pretty useful in most cases. But it is not so good and reasonable for short-lived TCP connections. Hence the question:
Should TCP slow start be used with SIP-over-...
- 207
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1
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3k
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Using DTMF signals of a VoIP gateway when interacting with an analog ministation (PBX) [closed]
There is such a configuration:
Internet ===> [WAN port] Grandstream HT812 with hosted PBX users [FXS ports] ===> analog ministation Panasonic ===> analog telephone sets
Situation: When a caller ...
- 1
1
vote
1
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427
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How to run SIP phones in the LAN (NAT Overloaded to single IP)?
We have a small office network switch connected to a DSL modem for internet and telephony access. Now we would to extend network to another location in the same building for which I deployed a cisco ...
- 113
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276
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Changing DSCP values in a Cisco Switch [closed]
We have an endpoint which cannot tag outgoing RTP packets as 46 (EF)....
Currently they happily churn out as 0
Can the Cisco switch it is entering, recognise it's RTP traffic and then change the ...
- 583
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1
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155
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Replacing IP address of connections from AWS towards SIP
We have installed a PBX on AWS and connected it to our on-prem Router via VPN.
My on-prem router is connected to the SIP provider via a physical connection with another on-prem MUX device (device ...
- 11
1
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0
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122
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SIP message, Via, Call-ID and Contact headers [closed]
In a SIP message, how is the "Via" header set?
If the value that appears in that header doesn't look correct, how can it be altered using Cisco command(s)?
Same questions for the "Call-ID" header, ...
- 399
1
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1
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1k
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IP is getting through from firewall although it was in Banned List
I am facing wearied scenario. We are having a SIP gateway in DMZ, yesterday I have observed malicious traffic hitting SIP gateway from the 212.x.x.209 IP. I immediately Banned this IP in firewall so ...
- 1,374
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3
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3k
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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.
As I understand it, it's important to maintain QoS on an internal network (i.e. prioritize VOIP traffic). Is this not ...
- 203
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168
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HP MSR2004 router is not processing udp through nat
I set up a new HP MSR2004 router for a corporate network. The network uses an internal private net and has one static public ip address. Surfing the web and all tcp related things seem to work fine. ...
- 171
3
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0
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94
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Configure C1861 for SIP to FXS port [closed]
I found a C1861 ISR router and I would like to play with it a learn some telephony.
I signed up for a VOIP service so I have SIP credentials. Is there a simple walkthrough anywhere to set up the SIP ...
- 43
2
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2
answers
425
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Forward single DID number to sip trunk
I am stuck on a project and need help. I have setup a SIP trunk on Cisco 2900 router to another vendors call server which is based on asterisk(custom application). We have phones register with the ...
- 43
1
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1
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700
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SIP alg on juniper SRX100H2
I'm not sure how the SIP alg on juniper works, but I guess its reading traffic on port 5060 to read sip signaling.
We have just changed to an other operator who dont use the standard sip port (5060) ...
- 113
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1
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795
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Cisco 7960 SIP phone background image issues
I have an asterisk home PBX and I recently got a Cisco 7960G on eBay. So far I got everything working but the background images are quite tricky. I followed one short how-to and I was able to actually ...
- 151
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1
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5k
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Cisco ASA SIP/RTP inspection question
I have following scenario:
[VoIP phone]--------[ASA 5550]----------[SIP Server]
VoIP phone: 10.0.0.10
SIP server: Public Address
Question:
In above scenario do i need to specify or open RTP ...
- 4,389
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1
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123
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How can I spoof a UK caller ID from the US? [closed]
I own several phone numbers in the United Kingdom that my UK customers can call to reach my business in the US. When we call UK customers from our US-based phones, we want the UK customers to see our ...
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1
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110
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VoIP Provider and Phone Number Routing Questions
I am fairly familiar with VoIP and I have my own VoIP PBX, and my provider is Twilio (for Voice) and CallCentric (for Fax). But How do providers like Twilio work exactly? More specifically:
How do ...
- 207
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2
answers
980
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IP Addresses of SIP packets [closed]
On this website, it says that
This shows the source and destination IP addresses of the SIP packet. Note this information will change as the packet passes between
SIP proxy servers.
I'm ...
- 143
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2
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982
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Convert encrypted SRTP to RTP for private network [closed]
Let's say that Alice would like to make SIP call to Bob. Alice initiates the call using her mobile device over a cellular network. On the other hand, Bob sits in a local network of an organisation. ...
2
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1
answer
2k
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Difference between sip proxy and sip outbound proxy? [closed]
What is the basic difference between a sip proxy and a sip outbound proxy. Can sip proxy and outbound proxy be the same?
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204
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Basic SIP system [closed]
I have been tasked to create a simple local SIP system. We have two Snom 710 phones and we just want one to call the other. We have tried Freeswitch and 3CX. It seems that we are missing something.
...
5
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2
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6k
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Can't configure the Cisco CP-8851 IP Phone
I do not have a cisco contract or license, but I did order the Cisco CP-8851 IP Phone from Amazon, and was hoping that I could configure it to work with my VoIP SIP PBX. But I can't seem to log into ...
- 207
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72
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Issue with voice performance between two ip phones at the same site connecting to two different CUCM?
I have one branch which is (branch-1) with two groups of ip phones, one group is connecting to CUCM-1 in HQ and the other group is connecting to CUCM-2 in the branch (branch-1) and the connectivity ...
4
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2
answers
17k
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SIP through ASA without inspection
After talking to a few hosted VoIP providers, they all state that "ALG" or SIP inspection in the case of the Cisco firewall should be disabled. How is SIP not broken after leaving the firewall over ...
- 7,134
3
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3
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2k
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What is the exact engineering involved behind creating a SIP trunk for any customer?
When a company is setting up a PBX and wants to use a SIP trunk, why does it have to buy it? Is there no way to provide itself with one on its own?
- 141
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3k
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Dedicated SBC really required for SIP trunking through a FortiGate 200B firewall?
I work at a school with a mid-sized ShoreTel deployment; two ShoreGear T1 trunk units and 15 ShoreGear 120/24 switches. We have a couple hundred IP phones and a couple hundred analog extensions (dorms)...
- 123
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0
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826
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Cisco CME Failing to Transfer Calls From SIP Trunk, via Watcher Button [closed]
So, I have run into an issue that is stumping me. I have a Cisco 2811 running 15.1(3)T4, and I am using it to run CME on a small (three phone) VoIP system. The system has a SIP trunk through Vitelity. ...
- 53
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191
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Small Business SIP Fail over multiple ISP's
Currently using a sonicwall but looking... small organization but calls are important.
Is there a way to do a failover between two different ISP's and NOT have the sip traffic drop. We use a ...
- 21
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2
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3k
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Cisco ASA 5500 configuration - SIP ports other than 5060
Is it correct that the SIP inspection in the ASA 5500 firewalls only kicks in for traffic on port 5060?
The referenced document below states so (this doc is specifically for the newer generation 5500-...
- 223
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1
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6k
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Double-NAT's Effects on SIP and RTP
What effects does double-NAT have on VoIP? What happens to the traffic in this type of situation and what conditions can occur as a result of it?
- 963
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How can the SIP timeout on a Cisco PIX be increased for the REGISTER transaction type?
A client app that registers through a PIX to a 3rd party SIP provider shows a 0:03:00 timeout. The client automatically reregisters every 5 minutes and doesn't appear configurable. After 3 minutes, ...
- 7,134
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2
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530
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If SIP(Session Initiation protocol) can get the user IP then why need STUN or TURN? [closed]
As said that SIP can locate the user IP with the user's SIP address, then why we need STUN or TURN?
- 235
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1
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859
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QoS for IP PBX behind DOCSIS modem (SIP trunk without direct routing by ISP)
I want to run a PBX behind a firewall behind a DOCSIS modem. Our ISP does not want to deploy a TA / gateway at our site. Our ISP only uses the modem for analog telephony and nothing else. QoS for ...
- 860
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389
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Cisco callmanager SIP features
I am a programmer working in a software for the sales dept. I would like to know if a feature I want to implement is possible or not.
The user has an application where he can see information about a ...
- 183
4
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1
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9k
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UDP Port Forwarding Range
We just purchased a cisco 3825 router running IOS 15.1. The slice of the
topology in question is as follows:
RTP (8000-20000) RTP (8000-20000)
192.168.2.1 <-------------->...
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