SPA3102 - Incorrectly formatted SIP frame

scruffybob · #1 (**permalink**) January 3rd, 2009, 06:23 AM

I've got a bunch of SPA3102's that I'm using to convert from my analog PSTN to SIP to pass to my 3CX IP-PBX. Everything works great, except when I receive a Caller-ID NAME from the PSTN that has a comma embedded in it. The 3102 sends it's INVITE packet with the display name as received and the 3CX (correctly) discards the packet since the display name has embedded special characters that are not quoted. This means that any incoming call with a caller ID containing a special character gets silently dropped by the PBX. Not exactly what I was looking for.

I'm running firmware 5.1.7(GW), but the problem also occurs with the 3.3.6(GW) firmware.

The SPA3102 has a field called "Escape Display Name" under the SIP parameters that I would guess should quote the display name, but setting it to "Yes" does nothing.

If I disable passing the PSTN caller-ID, then the SPA3102 uses the Display Name out of the Subscriber information as the Display info it passes on the INVITE. In this case, the "Escape Display Name" will quote the display name if the field is set to "Yes" and will not quote the display name if the field is set to "No", so I'm absolutely sure I'm getting the field set appropriately. However, quoting the field that I statically entered in another place isn't overly interesting. I need it to quote the incoming caller id name as passed in from the telephone company.

In fact, as I tried to figure this out, I tried to use the PSTN CID Name Prefix (under the PSTN tab) as a way to get it to quote the CID Name. What I found is that you can enter any special characters you'd like (commas, quotes, etc.) and it will happily generate an illegally formatted INVITE packet on it's own by pre-pending these characters to the passed name. I'm actually a little shocked that you can get it to generate illegal frames so easily.

This is killing me, as my only recourse seems to be to disable incoming Caller-ID altogether. Since incoming call flow is a big reason I want to convert to an IP-PBX, it makes the SPA3102's worthless if I can't resolve this issue. I didn't have much luck on the Linksys forum (the only suggestion there was to not use commas)

I used Wireshark to sniff the network to verify that the SIP packet generated by the SPA3102 is improperly formatted.

According to packets grabbed by wireshark, the INVITE from the SPA3102 goes out with the following FROM field:

From: MACKEY, RON E <sip:6303578135@192.168.2.132>;tag=b9c8ff5d2616dc0 3o1

The ASCII version:
0000 46 72 6f 6d 3a 20 4d 41 43 4b 45 59 2c 20 52 4f From: MACKEY, RO
0010 4e 20 45 20 3c 73 69 70 3a 36 33 30 33 35 37 38 N E <sip:6303578
0020 31 33 35 40 31 39 32 2e 31 36 38 2e 32 2e 31 33 135@192.168.2.13
0030 32 3e 3b 74 61 67 3d 62 39 63 38 66 66 35 64 32 2>;tag=b9c8ff5d2
0040 36 31 36 64 63 30 33 6f 31 0d 0a 616dc03o1..

Does anyone know how to get the Caller ID NAME quoted properly as it's passed from the PSTN to the VOIP gateway, or at least is there any way to pass the incoming Caller ID from the PSTN but NOT pass the Caller ID Name? As long as I can get the ID, I can work around not getting the name.

Best regards,
scruffy-bob