06-11-2025 12:14 PM
Hello,
I lack the knowledge when it comes to Voice Telecom.
We have a small remote office in a location where the options to choose ISPs is very limited. There is only a single ISP in region. We need to provide have Voice services in this office and our ISP offered us POTS lines. Our SI (Systems integrator) sent us an estimate (below) for the recommended VG (Voice Gateway) that will be used to connect these POTS lines, however, the SKUs included seem a bit overkill. I was wondering if one of you voice\VoIP experts could guide me select the appropriate SKUs to simply connect this remote office using POTS lines? Also, our SI advised to use this VG as an SRST router to support the VG located at HQ.
Thanks in advance.
Cisco | C8300-2N2S-6T | Cisco Catalyst C8300-2N2S-6T Router |
Cisco | PVDM4-256 | 256-channel DSP module |
Cisco | NIM-2MFT-T1/E1 | 2 port Multiflex Trunk Voice/Clear-channel Data T1/E1 Module |
Cisco | C-SM-NIM-ADPT | Cisco Catalyst SM to NIM Module Adaptor |
Cisco | NIM-4FXO | 4-port Network Interface Module - FXO (Universal) |
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06-11-2025 04:23 PM - edited 06-11-2025 04:25 PM
To add to my previous reply I would say that generally a Catalyst 8300 2N2S-6T is overkill for the number of users you're looking at. I would say that you do not need anything larger than Catalyst 8200 1N-4T.
06-12-2025 12:29 PM
Hi @ZK916,
Thank you for your clarification.
Yes, the Cisco C8200-1N-4T does support SRST (Survivable Remote Site Telephony) functionality. You can safely go ahead with this platform for your remote site, especially considering your current requirement is only for 6 POTS lines and around 250 users. It's more than sufficient for this kind of setup.
Regarding the SRST license, yes—SRST does require a separate license, known as SRST feature license or UC license under newer Smart Licensing models. Usually, this is tied to the number of users you intend to support during WAN failure. For 250 users, you’d procure a corresponding SRST user license pack.
Also, to keep things simple:
The NIM-4FXO module is the right choice to connect your 6 POTS lines (you can use two of these to support up to 8 lines).
There is no need for the NIM-2MFT-T1/E1 module if you are not using PRI circuits.
The PVDM4-256 is indeed an overkill if you’re only using FXO and don’t plan on doing advanced media services (like conferencing or transcoding). Each FXO NIM has built-in DSPs sufficient for standard analog calls.
If your future plan includes PRI or media-heavy functions, you can always revisit the DSP and module requirements then. But for now, I’d suggest keeping the design simple and practical.
06-11-2025 12:26 PM
Hi @ZK916,
Please let me know below details:
How many users are located at remote location?
How many POTS lines are you going to connect on the router?
Are you going to use PRI lines as well? If yes, how many?
06-11-2025 12:38 PM
Hello, Vaijanath,
- Number of users will be 250
- Number of POTS lines will be 6
- No, we will not use PRI lines
Thanks.
06-11-2025 04:19 PM
Are there any specific reason why your SI have added a NIM card with 2 PRIs as you're saying that you'll not going to use PRIs? Also are there any specific reason for why they have added the PVDM 256 DSP module? If all that you'd be using is FXO ports you do not need to have additional DSP resources as these cards already have built in DSP resources. There might be there for another reason, like use for media resources like transcoders and/or conference bridge, but without knowing a little more on your specific use case we can't really tell you if that is needed. What I would say is that even if you'd be using that a 256 channel module sounds like an overkill for 250 users.
06-11-2025 04:23 PM - edited 06-11-2025 04:25 PM
To add to my previous reply I would say that generally a Catalyst 8300 2N2S-6T is overkill for the number of users you're looking at. I would say that you do not need anything larger than Catalyst 8200 1N-4T.
06-12-2025 12:17 PM
Thanks, Roger.
Out SI added the NIM card with 2 PRIs and the PVDM 256 DSP module for future proofing and investment protection. The consultant mentioned that since we intend to have this VG setup as a SRST, we should add those NIMs and modules.
I like the idea of getting the C8200-1N-4T, however, would this particular platform support the SRST role? Does the SRST require a separate licensing?
Thanks in advance.
\
~zK
06-12-2025 05:19 PM
All router models sold now with UC services supports SRST. Yes it’s a licensed feature.
06-12-2025 12:29 PM
Hi @ZK916,
Thank you for your clarification.
Yes, the Cisco C8200-1N-4T does support SRST (Survivable Remote Site Telephony) functionality. You can safely go ahead with this platform for your remote site, especially considering your current requirement is only for 6 POTS lines and around 250 users. It's more than sufficient for this kind of setup.
Regarding the SRST license, yes—SRST does require a separate license, known as SRST feature license or UC license under newer Smart Licensing models. Usually, this is tied to the number of users you intend to support during WAN failure. For 250 users, you’d procure a corresponding SRST user license pack.
Also, to keep things simple:
The NIM-4FXO module is the right choice to connect your 6 POTS lines (you can use two of these to support up to 8 lines).
There is no need for the NIM-2MFT-T1/E1 module if you are not using PRI circuits.
The PVDM4-256 is indeed an overkill if you’re only using FXO and don’t plan on doing advanced media services (like conferencing or transcoding). Each FXO NIM has built-in DSPs sufficient for standard analog calls.
If your future plan includes PRI or media-heavy functions, you can always revisit the DSP and module requirements then. But for now, I’d suggest keeping the design simple and practical.
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