Introduction
This document describes how to determine the VM (Virtual Machine), vCPU, and RAM resources (or a VM instance for cloud-related deployments) required for an
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deployment to support an enterprise's planned maximum SIP session density. The
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session capacity varies in proportion to the vCPU and RAM resources assigned to the VM host; improper assignment of vCPU and RAM resources to a VM may result in
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being unable to service the required enterprise session workload. Deploying an SBC SWe Lite instance applies to the following:
Definitions and Terminology
Term | Definition |
---|
Default RTP Media Manipulation Mode Scenario | A bi-directional IP-based RTP ↔ RTP media manipulation mode session scenario providing G.711 (RTP) ↔ G.729ab (SRTP) transcoding services. This is the suggested RTP media manipulation scenario when determining a VM's vCPU and RAM resource requirements. |
RTP Media Manipulation Mode Session | A bi-directional IP-based RTP ↔ RTP media session that receives services from the virtual DSP (Digital Signal Processor) logic within the Unable to show "metadata-from": No such page "_space_variables" . Virual DSP services include translation of media from one codec to another ("transcoding"), encrypting/decrypting media, in-band tone detection, enhanced interoperability, improved user experience, and other media-related services that require direct access to the media flow and information. |
RTP Media Session | A bi-directional flow of audio, video, or other real-time information (such as FAX) between two endpoints that may or may not directly transit the SBC. |
RAM | Random Access Memory. Refer to Random Access Memory. For Unable to show "metadata-from": No such page "_space_variables" planning, RAM requirements are always presented in integer GiB multiples (https://en.wikipedia.org/wiki/Gibibyte ). |
vCPU | Refer to https://www.quora.com/What-is-the-difference-between-a-core-a-virtual-CPU-and-a-thread. For Unable to show "metadata-from": No such page "_space_variables" planning, vCPU requirements are always presented in integer vCPU multiples. |
Concepts
Description
RTP direct media mode sessions do not flow through the
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. These flows are common with endpoints that reside within the same physical premises (such as a single branch office) where there is no need for any manipulation of any aspect of the media flow (such as codecs, headers, and encrypting/decrypting). The implications of such sessions on the
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are:
- Multiple direct media mode session streams (audio, video, and so on) may be associated with a given SIP session, and do not require additional licensing unless identified elsewhere.
- Only one mode of media is supported against a given SIP session. For example, one stream of media in direct media mode and one stream of media in RTP proxy media mode, cannot both be associated with the same SIP signaling session.
Licensing
The
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supports a single RTP media session on a 1:1 basis with an associated SIP signaling session. Note the following:
Refer to Working with Licenses for a description of available
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SIP session licenses that include support for RTP direct media mode session, as follows:
- For KVM, VMware, Microsoft Hyper-V on-premises SBC SWe Lite deployments, all SIP session licenses that end with the following characters: -SG, -SGX, -SP
- For Microsoft Azure cloud-based SBC SWe Lite deployments, all SIP session licenses that end with the following characters: -SG
-CLOUD, -SGX-CLOUD, -SP-CLOUD
Description
These flows are common with endpoints that do not reside within the same physical premises, but do reside within the same enterprise. If these sessions require access to a public SIP trunk (call flows out of the corporate WAN), there may be a need for encryption/decryption and IP address manipulation services. Many public carriers do not support the forwarding of encrypted media or private IP addresses. However, complex media manipulation such as transcoding is not required due to enterprise-wide policies surrounding codec usage being in force. The implications for these sessions include:
- Multiple RTP proxy media mode session streams (audio, video, and so on) may be associated with a given SIP session, and do not require additional licensing unless identified elsewhere.
- Only ONE mode of media is supported against a given SIP session. For example, with one stream of media in direct media mode and one stream of media in RTP proxy media mode, both cannot be associated with the same SIP signaling session.
Licensing
The
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supports a single RTP proxy media mode session on a 1:1 basis with an associated SIP signaling session. Note the following regarding RTP proxy media mode sessions:
Refer to Working with Licenses for more information about SIP session licenses that support RTP proxy media mode sessions:
- For SIP sessions requiring no support for encryption/decryption services within the context of RTP proxy media mode sessions:
- KVM, VMware, Microsoft Hyper-V on-premises SBC SWe Lite deployments, all licenses that end with the following characters: -SG, -SGX, -SP
- Microsoft Azure cloud-based SBC SWe Lite deployments, all licenses that end with the following characters: -SG
-CLOUD, -SGX-CLOUD, -SP-CLOUD
- For SIP sessions requiring support for encryption/decryption services within the context of RTP proxy media mode sessions:
- KVM, VMware, Microsoft Hyper-V on-premises SBC SWe Lite deployments, all licenses that end with the following characters: -SGX, -SP
- Microsoft Azure cloud-based SBC SWe Lite deployments, all licenses that end with the following characters: -SGX-CLOUD, -SP-CLOUD
Description
A media session requiring media manipulation is labeled an RTP media manipulation mode session. Such flows are common with endpoints that communicate across enterprise and public boundaries. The
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delivers RTP media manipulation services through the application of virtual DSP (Digital Signal Processing) feature to the media session. The media manipulation services delivered by the
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include:
- Transcoding. This includes G.711 (common codec in enterprises) ↔ G.729ab (common codec in public networks) translation, and G.711 A-law ↔ G.711 µ-law. Refer to Protocols and Protocols and Functions Supported for the list of codecs.
- Transrating. Transrating includes call legs that carry a different time sample size of media, where the
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performs the translation. Transrating is used often when enterprises or the service provider is looking to save bandwidth by reducing packet count at the expense of voice quality (should a packet be dropped). - Silence suppression. The
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looks to remove/insert RTP packets carrying no meaningful media to save packet traffic. - Fax calls.
- Fax tone detection and interworking to T.38
- G.711 fax media pass-through, as DSP intervention reduces the likelihood of in-band fax signaling/media issues
- In-band ↔ out-of-band interworking. Required for the following:
- In-band DTMF tone detection interworking with out-of-band RFC 4733 (supersedes RFC 2833)
- In-band DTMF tone detection interworking with SIP INFO messages
- Interworking RTP dynamic payload types, required when the subtended SBC peers use differing payload type identifiers from the dynamic RTP payload range (for example 96 - 127) to identify a common payload format (in other words, codec)
- Media that originates from the SBC in support of call developments. For example:
- Announcement playback
- Local ringback tone
- Music on Hold
- Comfort noise
- Jitter compensation. Used to maximize user experience with voice quality.
- Certified Skype for Business/Teams Phones and Devices interworking with non-certified endpoints. With virtual DSP intervention,
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s can address media incompatibility issues between certified Skype for Business Server endpoints (Refer to https://technet.microsoft.com/en-us/office/dn947482) and other SIP-based client endpoints, such as RTCP reporting interval mismatch, and unrecognized in-band supplementary service requests.
The implications of RTP media manipulation mode sessions are the following:
- The
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consumes VM RAM and vCPU resources to deliver RTP media manipulation services via the virtual DSP feature. - Consumption of a VM's RAM and vCPU resources is higher when delivering RTP media manipulation services than the consumption of RAM and vCPU resources associated with RTP proxy media mode services.
Consider RTP media manipulation mode session density to determine a VM's vCPU and RAM resources for a specific
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.
RTP Media Manipulation Mode - Notes
- The virtual DSP (within the context of an RTP media manipulation mode session) supports complete encryption/decryption services, such as RTP ↔ SRTP conversions, cipher change, & authentication algorithm change.
- Multiple RTP media manipulation mode session streams (audio, video, and so on) may be associated with a given SIP session, and do not require additional licensing unless identified elsewhere.
- Only one mode of media is supported against a given SIP session; for example, you cannot have one stream of media in RTP media manipulation mode, one stream of media in RTP proxy media mode, both associated with the same SIP signaling session.
Licensing
The
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supports a single RTP media manipulation mode session on a 1:1 basis with an associated SIP signaling session. See below.
Refer to Working with Licenses for a description of available
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SIP session licenses that include support for RTP media manipulation mode sessions. See below.
- For SIP sessions requiring no support for transcoding but support for all other RTP media manipulation services:
- KVM, VMware, Microsoft Hyper-V on-premises SBC SWe Lite deployments, all licenses that end with the following characters: -SGX, -SP, -ME
- Microsoft Azure cloud-based SBC SWe Lite deployments, all licenses that end with the following characters: -SGX-CLOUD, -SP-CLOUD, -ME-CLOUD
- For SIP sessions requiring support for transcoding over and above other RTP media manipulation services:
- KVM, VMware, Microsoft Hyper-V on-premises SBC SWe Lite deployments, all licenses that end with the following characters: -SP, -ME
- Microsoft Azure cloud-based SBC SWe Lite deployments, all licenses that end with the following characters: -SP-CLOUD, -ME-CLOUD
Session Density Map
The table below is a guide to the maximum capacity of an
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configured into a VM (Virtual Machine) with a given set of vCPU and RAM resources. The maximum number of the following items vary depending upon a given VM resource profile:
- RTP media manipulation mode sessions
- RTP proxy session mode sessions requiring encryption/decryption services
- RTP proxy session mode sessions not requiring encryption/decryption services
- Direct media mode sessions (not presented in the table, but equivalent to RTP proxy session mode sessions not requiring encryption/decryption services)
- SIP registrations.
Use the tables below to identify and plan the required resource configuration for a given deployment of an
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to address SIP traffic flow.
Call Performance - KVM, VMware, Microsoft Hyper-V On-Premises Deployments
SWe Lite Virtual Machine Resources, applicable to all supported hypervisors (KVM, VMware® Microsoft Hyper-V) | Maximum SIP with corresponding RTP Media Sessions1 | SIP Signaling Session Limits | RTP Media Session Limits | Maximum Call Rate Setup (CPS) |
Media Manipulation Mode2 (Requires Virtual DSP Intervention) | Proxy Media Mode (No Virtual DSP Intervention) | Audio/Video Streams3 |
vCPU # | GB RAM | Maximum TCP/TLS-based SIP↔SIP Signaling Sessions | Maximum SIP Registrations (60 minute refresh rate) | No transcode, with in-band services scenario | Default scenario: G.711/G.729ab RTP ↔ G.729ab/G.711SRTP, with in-band services | Encryption services: G.711 RTP ↔ G.711 SRTP | No encryption services: RTP ↔ RTP/SRTP ↔ SRTP |
1 | 1 GiB | 100 | 300 | 1000 | 100 | 100 | 3006 | 3006 | 25 | 10 |
2 | 1.5 GiB | 1000 | 1000 | 1000 | 200 | 200 | 10006 | 10006 | 50 | 10 |
4 | 2.5 GiB | 1000 | 10004/6005 | 5000 | 4504/6005 | 4504/6005 | 10006 | 10006 | 100 | 10 |
10 | 2.5 GiB | | | 5000 | | | | | 100 | 10 |
1Maximum number of concurrent sessions. The number assumes that calls are made using RTP/SRTP Proxy mode, or a mix of RTP/SRTP Proxy, media manipulation and video calls.
3Maximum number of concurrent audio/video sessions. The total system capacity is affected if A/V calls are introduced into the call mix. Maximum number of calls is reduced by the number of video streams used. For example, 1 vCPU instance processing 25 A/V calls has a total capacity of: 300 (max number of calls) - 25 (calls processed with 1 vCPU instance) = 275 calls.
4Maximum number of concurrent sessions (when virtual DSP intervention is applied to 450 sessions) is 1000.
5Maximum number of concurrent sessions (when virtual DSP intervention is applied to 600 sessions) is 600.
6Maximum number of proxy media mode concurrent sessions is reduced by a count equivalent to the active number of concurrent RTP media manipulation sessions. Refer to note 1.
Call Performance - Microsoft Azure Cloud
Azure Virtual Machine (VM) Resources | Maximum SIP with corresponding RTP Media Sessions1 | SIP Signaling Session Limits | RTP Media Session Limits |
Media Manipulation Mode2 (Requires Virtual DSP Intervention) | Proxy Media Mode (No Virtual DSP Intervention) |
VM Instance | vCPU | Maximum TCP/TLS-based SIP↔SIP Signaling Sessions | Maximum SIP Registrations (60 minute refresh rate) | No transcode, with in-band services scenario | Default scenario: G.711/G.729ab RTP ↔ G.729ab/G.711SRTP, with in-band services | Encryption services: G.711 RTP ↔ G.711 SRTP | No encryption services: RTP ↔ RTP/SRTP ↔ SRTP |
B1MS | 1 | 10 | 10 | 100 | 10 | 10 | 103 | 103 |
F1s | 1 | 300 | 300 | 1000 | 100 | 100 | 3003 | 3003 |
F2s | 2 | 1000 | 1000 | 1000 | 200 | 200 | | 10003 |
F4s | 4 | 1000 | 1000 | 5000 | 400 | 400 | | 10003 |
1Maximum number of concurrent sessions. The number assumes that calls are made using RTP/SRTP Proxy mode, or a mix of RTP/SRTP Proxy, media manipulation and video calls.
2Maximum number of concurrent sessions with virtual DSP intervention. See Transcoding Capacity below for details.
3Maximum number of proxy media mode concurrent sessions is reduced by a count equivalent to the active number of concurrent RTP media manipulation sessions. Refer to note 1.
Number of RTP Port Pairs must be increased above maximum call capacity
The number of RTP Port Pairs must be configured slightly larger than the actual number of ports required to support the projected number of calls. We recommend you over-allocate the number of port pairs by approximately 25 - 30% above the number of calls you want to support. For details, see Configuring the Media System.
Call Capacity Limitations
- Call capacity is limited to 4 calls per second when Info level logging is enabled. Additional logging verbosity reduces the call capacity.
- Although the call setup rate is 10 calls per second, if Call Admission Control (CAC) is enabled, calls over the rate limit will be rejected with the message 480 Temporary Not Available.
Transcoding Capacity - KVM, VMware, Microsoft Hyper-V On-premises Deployments ()
Transcoding Capacity - KVM, VMware, Microsoft Hyper-V On-premises Deployments (1, 2, 4 vCPU)
Transcoding Scenario | Virtual Machine vCPU Count |
CODEC 1 | CODEC 2 | 1 vCPU | 2 vCPU | 4 vCPU |
---|
G.711A-law or G.711u-law | G.711A-law or G.711u-law | 100 | 200 | 600 |
G.711A-law or G.711u-law | G.723 | 80 | 160 | 480 |
G.711A-law or G.711u-law | G.726 or G.729 | 100 | 200 | 600 |
G.711A-law or G.711u-law | AMR WB | 38 | 76 | 225 |
G.711A-law or G.711u-law | Opus | 24 | 54 | 165 |
G.711A-law or G.711u-law | T.38 | 50 | 100 | 300 |
Transcoding Capacity - KVM, VMware, Microsoft Hyper-V On-premises Deployments (10 vCPU)
Transcoding Capacity - KVM, VMware, Microsoft Hyper-V On-premises Deployments (10 vCPU)
CODEC 1 | CODEC 2 | 10 vCPU |
---|
G.711A-law or G.711u-law | G.711A-law or G.711u-law | 1200 |
G.711A-law or G.711u-law | G.729 | 1200 |
Opus | G.711A-law/mu-law | 360 |
Transcoding Capacity - Microsoft Azure Cloud Deployments
Transcoding Capacity - Microsoft Azure Cloud Deployments
Transcoding Scenario | Microsoft Azure VM Instance |
CODEC 1 | CODEC 2 | B1MS VM | F1s VM | F2s VM | F4s VM |
---|
G.711A-law or G.711u-law | G.711A-law or G.711u-law | 10 | 100 | 200 | 400 |
G.711A-law or G.711u-law | G.726 or G.729 | 10 | 100 | 200 | 400 |
Process to Determine VM Resources
Identify and record the minimum quantity of VM resources to support your maximum default RTP media manipulation mode sessions:
For an on-premises Unable to show "metadata-from": No such page "_space_variables"
deployment, refer to Table 1 and record the required minimum quantity of vCPUs and RAM found in the vCPU # and GB RAM column that supports a number of default RTP media manipulation mode sessions greater or equal to your deployment need; note the number of supported default RTP media manipulation mode sessions is found in the Default scenario: G.711/G.729ab RTP ↔ G.729ab/G.711SRTP, with in-band services column.
For an Microsoft Azure-based
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deployment, refer to Table 2 and record the required minimum Azure VM instance type found in the VM instance column that supports a number of default RTP media manipulation mode sessions greater or equal to your deployment need; note the number of supported default RTP media manipulation mode sessions is found in the Default scenario: G.711/G.729ab RTP ↔ G.729ab/G.711SRTP, with in-band services column.
Use of Table 3 for non-default RTP media manipulation mode sessions
If on-premises
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deployment is required to support a transcoding scenario other than
G.711 ↔ G.729ab (the default RTP media manipulation mode session scenario), use
Table 3 to identify the required minimum quantity of vCPUs to assign to the VM. For example, support for 50
G.711 ↔ OPUS sessions requires 2 vCPUs. The 2 vCPU figure should be used when undertaking step 2(a).
Identify and record the minimum quantity of VM resources to support the additional RTP proxy session mode sessions (beyond the maximum default RTP media manipulation mode sessions) for your
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deployment.
Calculating the maximum available RTP proxy mode sessions for your VM resource
The maximum available RTP proxy session mode session capacity is not equal to a value found in the Maximum SIP with corresponding RTP Media Sessions column in Tables 1 or 2; rather, it is determined by subtracting the maximum default RTP media manipulation mode sessions identified in Step 1 from the Maximum SIP with corresponding RTP Media Sessions column value associated with the quantity of vCPUs and RAM recorded from Step 1.
Step | Action |
---|
a | For an on-premises Unable to show "metadata-from": No such page "_space_variables" deployment, refer to Table 1 and calculate the maximum available RTP proxy session mode session capacity with the quantity of vCPUs and RAM recorded from Step 1 (or Step 2 (b)). For an Microsoft Azure-based Unable to show "metadata-from": No such page "_space_variables" deployment, refer to Table 2 and calculate the maximum available RTP proxy session mode session capacity with the Azure VM instance type recorded from Step 1 (or Step 2(b)). |
b | Identify if the calculated maximum available RTP proxy session capacity from (a) above is larger than your required additional RTP proxy session mode sessions: If... | Then |
---|
Calculated capacity from 2 (a) is larger than required RTP proxy session mode sessions | Proceed to step 3, using the quantity of vCPUs and RAM determined from point 2(a) above. | Calculated capacity from 2 (a) is smaller than required RTP proxy session mode sessions | Review Table 1 (or Table 2 for an Azure-based deployment) and increase the quantity of vCPUs and RAM (or upgrade to a more powerful) Azure VM, then re-execute step 2(a). |
|
- Prepare to configure your
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with the resources arrived at the end of step 2.For an on-premises
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deployment, refer Installing SBC SWe Lite.- For an Microsoft Azure-based
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deployment, refer to Running a SWe Lite via Microsoft Azure Marketplace.
Examples
Calculating a VM's vCPU and RAM Resource Requirements for an On-premises Low-Density KVM-based
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Deployment- Fifty (50) RTP media manipulation mode sessions are required (a session is equivalent to the Default RTP Media Manipulation Scenario defined above).
- A single vCPU and 1 GiB of RAM is the minimal vCPU and RAM count that supports this number of RTP media manipulation sessions.
- Record these values as the potential number of vCPU and RAM resources to assign to the VM hosting the
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.
- One hundred (100) additional RTP proxy session mode sessions services are required.
- A single vCPU and 1 GiB of RAM supports a maximum of 300 total SIP with corresponding RTP sessions. Subtract the 50 RTP media manipulation mode sessions from the 300 and there are 250 remaining sessions.
- 250 sessions is greater than the 100 additional RTP proxy session mode sessions; run concurrent to the 50 RTP media manipulation mode sessions, and use the 1 vCPU and 1 GiB RAM resources identified from point 1.
- Refer to the Installing SBC SWe Lite on KVM Hypervisor to configure a VM with 1 vCPU and 1 GiB RAM to host the
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.
Identifying the Microsoft Azure VM Instance for a Cloud-based
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Deployment- 200 RTP media manipulation mode sessions that support G.711 ↔ G.729ab transcoding are required.
2. 800 additional RTP proxy session mode sessions are required.
- The F2s VM supports 1000 SIP with corresponding RTP media sessions.
- Subtract the 200 RTP media manipulation mode sessions from the 1000, and 800 sessions remain.
- Record the F2s VM instance as the 800 sessions determined previously is equal to the 800 additional RTP proxy session mode sessions required to run concurrent to the 200 RTP media manipulation mode sessions.
3. Refer to Running a SWe Lite via Microsoft Azure Marketplace to start an F2s VM hosting the
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.
Calculating the vCPU and RAM Resource Requirements for an On-premises High-Density Hyper-V based
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Deployment- 200 RTP media manipulation mode sessions are required to support G.711 ↔ AMR WB transcoding.
2. 800 additional RTP proxy session mode sessions with encryption/decryption services.
- From Table 1, I see 4 vCPU and 2.5 GiB of RAM supports 1000 SIP with corresponding RTP media sessions are required.
- Subtract the 200 RTP media manipulation mode sessions from the 1000, and 800 sessions remain.
- Record the 4 vCPU and 2.5 GiB RAM figures; the 800 session figure determined previously is equal to the 800 additional RTP proxy session mode sessions required to run concurrent to the 200 RTP media manipulation mode sessions.
3. Refer to Hyper-V installation guide to begin the process of instantiating a VM with 1 vCPU and 1 GiB RAM to host the
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.
Calculating the vCPU and RAM Resource Requirements for a High-Density SIP Registration
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DeploymentThe required vCPU and RAM for a high capacity SIP Registration deployment are relatively simple: if the number of SIP registrations exceeds 1,000 endpoints, configure the VM with a minimum of 4 vCPUs and 2.5 GiB RAM. If less/equal to 1,000, the RAM is defined by the required session capacity.
SIP Signaling Group Considerations
SIP Signaling groups (provisioning constructs that represent a connection between the
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and another SIP based peer) can be configured to use either RTP media manipulation session mode or a RTP proxy session mode. See below:
Considerations for DTMF
There are several alternatives for DTMF calls:
- When a DTMF call is received, the
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terminates the call and transmits G.711. Other codec types may also be used. However, types such as G.723.1 may be less reliable. - When a DTMF call is received, the
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terminates the call and transmits the signals as out-of-band RFC 2833/4733 compliant messages or out-of-band SIP INFO messages. - A signaling group can be provisioned to transmit in-band signals as voice, RFC 2833/4733, or SIP INFO messages. There is no fall-back function.
- In the case of RTP proxy session mode, the
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does not process the DTMF.
Considerations for Video Interworking
The SBC SWe Lite supports 25 video streams per vCPU to a maximum of 100 streams. Exceeding 4 vCPUs does not allow more than 100 video streams.