SIP or GSM?

Question

Telephony

Early in my career, I was a computer helper.
Then I found a good well-paid job, but clients occasionally call me.
The other day I received a very interesting request from a potential client (came on the recommendation).
Given:
A person has a company and they want to organize a call center in it. The business is very seasonal. In addition to several full-time employees, there are agents in the regions of Russia.
The ratio of incoming calls to outgoing calls: 10/90
The volume of minutes is very large. Some agents and employees spend more than 3,000 minutes (the "unlimited rate" limit). After analyzing outgoing calls (to which operators calls are made), it turned out that the main operator is beeline.
What is required:
1.Optimize communication costs
2. Make sure that the addressee has a company number, not a federal mobile number.
3.Full unlimited beeline and inexpensive calls to other mobiles.
4. Recording conversations is not really needed.
5. Inexpensive implementation of telephone sets or clients on a computer.
6. It is not possible to install a server in the office, because employees rarely sit in the office. If only a cloud. Fault tolerance is not particularly critical.

I heard that there are gsm - gateways, but is it possible to implement several conversations at the same time through 1 gateway?

Answer 1

I do not think that you can get a thread with GSM gateways. The megaphone has a wonderful thing for such purposes - a multiphone. Beeline has sip only for outgoing calls if I'm not mistaken. In any case, you need to dig in the direction of SIP + asterisk on VDS which thread. IMHO.

Answer 2

The bulk of the calls are outgoing and they need to be made unlimited or get huge packages of minutes on the beeline. For incoming calls, you can purchase an 8-800 number with call forwarding.
The most important thing is cheap outgoing calls to beeline. So far, only Moscow. The regional segment will also gradually join.
Beeline has a tariff, which gives 60 minutes a day. You only need to replenish the balance by a certain amount. The amount of voice traffic is not very stable. Sometimes there are 15 minutes of conversations a day, and sometimes 4-5 hours.

Answer 3

The cheapest solution, in my opinion, is with a server in the office. If you are not going to drive hundreds of simultaneous calls, then the usual inexpensive desktop and the Internet at the rate of 1 call ~ 64 kbps will be enough there. However, you can compress up to 8 kbps. So, we deploy an asterisk on the server, take a USB hub and plug modems supported by the asterisk into it. For example Huawei E1750. You can also get a landline phone there, and connect a bunch of SIP operators, resolving the direction of outgoing calls by prefixes, codes, etc., etc.
I have something like this design spinning in general on the router. I get the number via SIP (multiphone), the GSM modem sticks out for insurance if the Internet falls off. It pulls a couple of calls, but I don’t need more.

Answer 4

Items 2 and 3 are not easy to reconcile. The cheapest solution is via GSM, but you can forget about determining the office number.
Solutions with the definition of an office one can be given by SIP operators, but there will not be a cost cheaper than 1.5-2 rubles per minute.
The only way to try to make "cheap and beautiful" is to look for an IP solution from the beeline itself, if it provides.

Answer 5

There are two ways to get cheap calls to beeline, one is through sim cards, but then I'm afraid I'll have to forget about the equipment outside the office and the client's normal number, the second is to connect all the services of the beeline and agree with him for unlimited, it's not a fact that it will work out, but I think it's possible .
It is better to implement everything through a virtual PBX from the provider. If you do your own on a hosting, then you need to have a very decent qualification in this area, otherwise it’s not very safe, then bills for 200t.r will come. for calls to Zimbabwe.
For field workers, there are also solutions from telecom operators. But why this is necessary for traveling employees is not very clear, it is normal to call via voip with a predictable quality of communication via gsm is problematic. Plus, in terms of money, any solution will still be more expensive than on-net packages from the operator.
So, leave gsm as travellers, install a virtual PBX or your own, make a redirect to a mobile phone, take everything from the beeline, call the rest through gateways.