Best choice of dongle or Bluetooth setup for trunk using RASPBX

I have setup raspbx on pi 3 model b+ and it works fine for small business IVR,kindly guide me with best suitable method and cost effective option to link GSM trunk was planning Chan dongle but kindly guide on supported dongles that works perfectly fine and easily be found in India, also have seen the option of bluetooth connectivity kindly guide me if the latter option is suitable and works reliably for trunking

IVRs are unlikely to work over GSM networks, where the mobile is the server, as GSM codecs aren’t compatible with DTMF and GSM’s use of out of band signalling towards the mobile is “for further study”. Your dongle is a mobile, as far as the network is concerned.

chan_dongle is third party software. I think there is little or no current support, but you should search out any support channels for it.

The codecs used for mobile networks, even those claiming wide band speech, are vocoder based, meaning that they are based on models of the human vocal tract. DTMF, if anything, is designed not to be creatable by the human vocal tract.

I believe chan_dongle is designed for Huawei dongles from about 2010.

but link mentions usb dongle to work but wasn’t aware of models easily available in India as supported models page is of year 2021, also was looking on using simple phone throyugh Bluetooth mode and wanted to know how well it works

I think any bluetooth support is third party, and even less used that Huawei dongles.

chan_mobile, which is the one that does bluetooth, is included with the Asterisk source code, but in the addons directory and it is only community supported. Nearly all the code is at least 5 years old, and most is more like 11+ years old.

Other points to note are that RPi based Asterisk is normally only used by hobbyists, e.g. home automation, not businesses. That’s partly for the self fulfilling reason that a lack of business use means there are few resources to support businesses, and also because the SD cards used are not designed to have high write cycle lifetimes, especially the cheap ones. They are intended to be mainly read.

The RPi was designed as an aid to teaching computer skills, not for use as part of a critical business system.

Most businesses with small telephony requirements tend to use cloud based VoIP systems. On the other hand, I suspect they don’t always pay adequate attention to business resilience in major natural disasters and as a result of hostilities, and they sometime have overoptimistic views of the capabilities of contended systems, like the internet, and virtual machine hosts.

Also, the richer countries are in the process of turning off their traditional phone networks, and moving to VoIP for the whole fixed network.

Also, the richer countries are in the process of turning off their traditional phone networks, and moving to VoIP for the whole fixed network.

I honestly don’t see how that is relevant to the hardware people use for running (typically) PBXs or small phone systems. The PSTN is separate from private telecom infrastructure, like PBXs. Maybe a point to say that traditional telephony’s future is at the edge rather than in the backbone.

General commentary: Raspberry Pi is very common nowadays in many smaller Asterisk setups (especially amongst hobbyists, as you point out). I was surprised at how quickly it caught on - so many people seem to use them. Some folks are even hooking TDM cards up to Rasperry Pi’s, as it’s a lot less space and energy than a traditional desktop or rack server. Never done it myself, but more and more people doing it, using Pi’s for use cases that never would have been considered seriously before.

The feedback I’ve heard is good in that for low traffic servers (say, no more than a couple hundred channels up at once), a Raspberry Pi has worked out nicely for a lot of people. I can’t personally vouch for it, but it seems to more and more the way of the future for a lot of lower end Asterisk use cases, particularly those that can’t be virtualized such as when full telephony support is required.

I interpreted simple phone as referring to a POTS line.

This context suggests that is definitely not the case:

Whatever “simple phone” means here, it’s not POTS. The OP probably meant something wireless, and should have used less ambiguous language.