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In addition to Sierra Wireless MC8775 3G modem, there’s now a new offering for Dell DW5550 (or Ericsson F5521gw, which is the same hardware) mini-PCIe 3G cards at Aliexpress.com, in the price range of $20. This is a newer hardware (the ones I received were manufactured in mid-2012), and it supports higher UMTS speeds and an CDC Ethernet interface in Linux.

This page refers to Ericsson F3507g card, but all instructions are relevant for DW5550. The device identifies itself as Dell DW5550, firmware version R3B01 (Command for retrieving the version: AT+CGMR).

Default Linux kernel 3.2.0 in Debian Wheezy names the CDC Ethernet interface as usb0, and 3.16.0 from Wheezy backports names it as wwan0. Other than that, everything else works the same.

Out of 3 ordered cards, two worked immediately, and one was broken. The seller has kindly offered a replacement for additional $10.

for n in `ls /sys/class/*/*{ACM,wdm,usb0}*/device/interface`;do echo $(echo $n|awk -F '/' '{print $5}') : $(cat $n);done usb0 : Dell Wireless 5550 HSPA+ Mobile Broadband Mini-Card Network Adapter ttyACM0 : Dell Wireless 5550 HSPA+ Mobile Broadband Mini-Card Modem ttyACM1 : Dell Wireless 5550 HSPA+ Mobile Broadband Mini-Card Data Modem ttyACM2 : Dell Wireless 5550 HSPA+ Mobile Broadband Mini-Card GPS Port cdc-wdm0 : Dell Wireless 5550 HSPA+ Mobile Broadband Mini-Card Device Management cdc-wdm1 : Dell Wireless 5550 HSPA+ Mobile Broadband Mini-Card USIM Port

The following commands initiate a 3G connection for a sunrise.ch SIM card:

apt-get install -y picocom ppp picocom -b 115200 /dev/ttyACM1 AT+CFUN=1 AT+CGDCONT=1,"IP","internet" AT*ENAP=1,1 Ctrl-a Ctrl-x dhclient usb0

This Debian wiki page explains how to bring up the connection automatically at Linux startup:

cat >/etc/chatscripts/sunrise.DW5550 <<'EOT' ABORT BUSY ABORT 'NO CARRIER' ABORT ERROR TIMEOUT 10 '' AT+CFUN=1 OK \dAT+CGDCONT=1,"IP","internet" OK \d\d\dAT*ENAP=1,1 OK EOT cat >/etc/chatscripts/gsm_off.DW5550 <<'EOT' ABORT ERROR TIMEOUT 5 '' AT+CFUN=4 OK EOT vi /etc/network/interfaces allow-hotplug usb0 iface usb0 inet dhcp     pre-up /usr/sbin/chat -v -f /etc/chatscripts/sunrise.DW5550 >/dev/ttyACM0 </dev/ttyACM0     post-down /usr/sbin/chat -v -f /etc/chatscripts/gsm_off.DW5550 >/dev/ttyACM0 </dev/ttyACM0
Filed under: Networking Tagged: 3G, GSM, linux, pcengines, UMTS

I needed to connect a GSM gateway to my FreeSWITCH PBX, in order to receive SMS and mobile calls and emulate a normal mobile phone. I’ve got the Yeastar Neogate TG200 V2 for this purpose (Firmware Version: 53.18.0.39, running Asterisk 1.6.2.6 on an ARM processor).

This blog entry has helped a lot and saved a bunch of time.

The box supports OpenVPN, so you can place it in some remote location behind NAT, and manage it via the VPN connection. The client version is rather old (2.0.5), so it does not support embedded certificates in the client config, and also “topology subnet” option is not supported. You need to pack your vpn.conf and the certificates and pivate key into a TAR archive and upload to Neogate via its web interface.

It’s sufficient to configure one SIP trunk to your PBX, and manipulate the To: header in order to distinguish between SIM cards on incoming calls.

When the SIP trunk was configured (FreeSWITCH as a registrar), I started receiving the following warnings on FreeSWITCH, and the registration status was quickly removed after neogate’s REGISTER message:

2014-12-22 12:29:42.208567 [WARNING] sofia.c:5721 Sip user 'gsm01@xxxxx.net' is now Unreachable 2014-12-22 12:29:42.208567 [WARNING] sofia.c:5732 Expire sip user 'gsm01@xxxxx.net' due to options failure

My FreeSWITCH was sending SIP OPTIONS requests to all registered users and removed the registrations unless the clients responded with status 200 or 468. Neogate responds with 404 Not Found on such requests toward the trunk SIP user. I had to disable “unregister-on-options-fail” option in FreeSWITCH internal SIP profile.

In SIP trunk configuration, “Advanced->Caller ID” was automatically set to my trunk’s registration user name. Because of this, all incoming calls had this name as the caller ID, and the original caller number was lost. After setting this field to blank, the problem was resolved.

In “Mobile to IP” rules, you can set a different rule for each SIM card. The “Hotline” field should not be blank, and should contain some distinguishing number. It will be used in To field in the SIP INVITE on incoming calls. If you leave “Hotline” empty, the Neogate will respond with dial tone and collect DTMF digits before placing the call to your SIP trunk. So far I could not find any documentation that describes this.

Also in trunk configuration, sometimes I had to reboot the box in order for my changes to take effect.

The box uses the standard Asterisk management interface for sending and receiving SMS, and I’m planning to use this Perl module through the VPN connection.

Filed under: Networking Tagged: freeswitch, GSM, pbx, voip

It’s not yet clear when I can start working on a new-generation Torrus, but here are some nice software projects which would probably inspire the new design, or probably be part of the new design. I haven’t looked into them in depth though.

• Bosun is a distributed monitoring system produced by StackExchange. It uses distributed collector agents which write data into OpenTSDB. Bosun and its collector are written in Go, and OpenTSDB is written in Java.
• InfluxDB is a time-series database written in Go.

and yes, the new project will most probably have its core in Go. But the SNMP discovery engine will most probably remain in Perl because of a big list of supported vendors.

Filed under: Programming Tagged: monitoring, network management, network monitoring, torrus

CEO Mike Leuthner discusses Phonami’s new Admin panel, allowing customers to activate Monster PBX accounts, setup billing, add and remove users directly from Google Apps. 

SendHub co-founder Ryan Pfeffer discusses a product overview, Kazoo at scale, and supporting WebRTC and Mobile.

2600hz and Voxbone discussing WebRTC at WeWork San Francisco, ….sorry for the poor audio quality

2600hz WebRTC Meetup at WeWork, San Francisco, CA from James Solada