I am looking for a GSM module for freepbx with support for several connections on one SIM card

(Templeusz) #1

Currently I have a Huawei GSM modem connected to FreePBX and I can make calls with it.

Unfortunately, the current configuration only allows one connection at a time

When I use this SIM card in my phone, I can call two different phone numbers and merge the conversation, i.e. I talk to two phone numbers at the same time.
Are there modules, modem or other GSM devices that will allow several connections to be made from one SIM card?


chan_dongle claims to have a ‘conference’ feature, but I don’t know whether it works with current Asterisk or whether it is reliable. Also, the ability to call more than two external numbers is dependent on the mobile operator.

What is your application (conference calling, connect outside parties together, ‘broadcast’ a message, etc.)?

What country are you in? Would a SIP trunk be suitable for your application?

(Dave Tech) #3

Have you considered using a 4G router and sim as the internet connection? This would give you the option of multiple voip channels


(Templeusz) #4

It turns out that Huawei modems only allow one connection

Yes, a GSM router can also be.
I need to make several calls at the same time from one SIM card.
What router has this functionality?


You can’t make multiple independent calls from one SIM card. When you make a conference call on an iPhone, there is only one path over the radio – the remote parties are all connected via a conference bridge at the mobile operator’s switch.

Please explain your application.

(Templeusz) #6

The idea was to use one SIM card and one device to make several calls at the same time using one SIM card.
Person A uses a VOIP telephone to call 500 400 400 using a SIM card, at the same time person B calls from another VOIP telephone to 500 400 401 using the same SIM card.

From the information received from you, I already know that it cannot be done.

(Dave Tech) #7

If you use the GSM card in a modem, then no you can only make one call.
If you use a 4G sim in a router using the router for a network connection then I would work on the basis that as long as you have enough sip channels on your trunk you can do what you like dependant on bandwidth of the connection.

Simply - your sim and router will no longer handle a voice call they will be handling data to the sip provider.


(Dave Tech) #8

obviously the sim needs a data plan, in uk any mobile broadband sim other than three is subject to CGNAT, three mobile - if you select 3internet as the APN is not.

After market m2m sims, data sims etc are widely available




If your intent is just to get inexpensive calls to PL mobiles, try one of the Betamax companies. Although users often complain about voice quality and reliability, there are also many customers who are very satisfied. You’ll have to risk 5€ (10€ for some brands) as there is no free trial. A pricelist for PL:
Click on the column headings to sort by price.
Avoid the brands with connection fees; you will likely choose supervoip or voipcaptain.

(Templeusz) #10

I changed my approach to the topic and I plan to achieve the target goal in a different way:
Buys a landline telephone number with 5 incoming lines from a voip provider.
Redirects incoming calls from the SIM card to the landline number of the voip provider.
Effect - 5 people can call me, and I can make 1 call at the same time and present my mobile number.

How to check which operators from this list allow the presentation of their own telephone number (telephone number from the SIM card)?

Do I have to use wholesale operators, e.g. AnveoDirect
Where can I find a list of operators who enable the presentation of their own telephone number (callerid), preferably it should be a Polish operator.