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Assistance appreciated - SPA3102 PSTN in > FreePBX no caller ID ? (Resolved :-) )

Hi everyone and a happy new year to you :-)

I'm in the UK and have a SIP service from along with a PSTN line provided by Virgin Media. Originally I used these  with a Siemens Dect VoIP system and this all worked nicely and provided inbound caller id to the handsets without issues.

I added a couple of Panasonic KX-UT133X SIP phones and set them up with RasPBX (basically Asterisk running on a Raspberry Pi) and the Sipgate trunk. All works nicely, I can place and transfer calls between the Panasonic / Siemens SIP phones and make and receive calls over Sipgate. The caller id is always shown correctly.

My good lady wife then asked why she couldn't transfer a call that had come in over the PSTN line to the SIP phones. Hmm... I needed a gateway and after a bit of Googling came up with the SPA3102. Once it arrived I updated the firmware to v5.2.13(GW002) and now have it in place and can route PSTN calls to my SIP phones without any voice issues - not even echo, which I've read can be a problem sometimes.

My problem is that i can't get the SIP phones to show the caller ID for the PSTN caller. My SPA3102 setup is as follows:

I'm not interested in dialling out over PSTN from a SIP phone, so I have the VoIP to PSTN Gateway and Line 1 both disabled to keep everything simple.

I have the PSTN to VoIP gateway enabled, and have it set so that it directly dials a ring group 500 which is set up on the RasPBX. The dial plan for this is (S0<sip:500@RasPBX IP address>)

I've set up the regional settings to suit UK, tried disconnecting the Siemens phone from the FXS port, tried setting the VoIP answer delay setting between 0 and 5, and PSTN CID for VoIP CID is set to yes.

I've googled extensively (how on earth did we do thigs like this before Google ? ) but haven't yet found the answer hence I'm open to suggestions from you clever people. Is this something that just won't work the way I'm doing it perhaps ?

Looking at SIP traces via the SPA3102 Syslog all I see where I'd expect to see caller id is 'Unknown'

Thanks in advance.

Kind Regards,


Everyone's tags (4)

Re: Assistance appreciated - SPA3102 PSTN in > FreePBX no caller

You need to have the PSTN Answer Delay set to an appropriate number of seconds to receive the incoming caller ID from your analog PSTN line before your dial plan dials your PBX extension. You said you had the VoIP answer delay setting between 0 and 5 but this isn't applicable to a PSTN-to-Voip Gateway call, it is the PSTN Answer Delay. 

The incoming caller ID on the analog PSTN line can come anywhere from just before the first ring to between the first and 2d ring.  If I remember correctly in the UK it comes after a polarity reversal before the first ring, at least with British Telecom.  You should see the incoming caller id detail in a sip debug trace with the Debug Level set to 3 on the System Tab  and the Sip Debug Option set to FULL on the PSTN Line Tab.

Community Member

Assistance appreciated - SPA3102 PSTN in > FreePBX no caller ID

Thank you for the pointers sir, I assume that if a polarity reversal is at play here I will also need to set the "Detect Polarity Reversal" field to yes too.

I think as I've been tweaking things for so long I may start by doing a full reset to defaults and then just set up the bare minimum config first. I'll come back later hopefully with good news.

Kind Regards,


Community Member

Re: Assistance appreciated - SPA3102 PSTN in > FreePBX no caller

Sorted !

Very bizarre - I was absolutely certain that I had seen caller id presented previously when i just had the Siemens Gigaset base station plugged directly into the PSTN socket, but his couldn't have been reliable. I tested the phone again this morning dialling into pstn from my mobile and there was no caller id.

I then discovered that Virgin in the UK don't enable caller id by default and that it's a chargeable add on. Had a chat with the nice man there who enabled it for me and now everything is working nicely.

I have seen caller id before though. I wonder if the caller id FSK tones are always present but at a very low level which is only very occasionally detected by the phone and never by the SPA3102 ? The only other thing I can think of was that the caller id was perhaps only showing on a pstn - pstn call where both parties are Virginmedia subscribers.

Anyway, all working now - telemarketers beware... apologies for maligning the SPA3102 !!

Kind Regards,


Community Member

Hi 99hwittenb, My SPA3102

Hi 99hwittenb,


My SPA3102 usage scenario is similar to this. I am using FreeSWITCH to route incoming call to approprite point. At the FreeSWITCH level, I am expecting the caller ID. I saw that caller ID is present in the syslog of 3102, but it is not passing that CID (From: field of SIP INVITE message) to FreeSWITCH. When 'User ID' is specified in 'Subscriber Information', that is passed. This is not a CID and remains static even the caller changes. If I omit 'User ID', nothing is passed. I did whatever settings are required including PSTN Answer Delay to 3 sec.

I am attaching the PSTN line configuration. Please have a look. Please help. I am stuck in this issue for last 2 weeks. I checked many threads in many forum but did not find any thead that is identical to my scenario.




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