# Asterisk sending INVITE without an SDP

**URL:** <https://community.asterisk.org/t/asterisk-sending-invite-without-an-sdp/88679>\
**Category:** Asterisk SIP\
**Created:** [May 20, 2021, 10:07am UTC](https://community.asterisk.org/t/asterisk-sending-invite-without-an-sdp/88679 "2021-05-20T10:07:15Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![brian\_j\_murrell](https://avatars.discourse-cdn.com/v4/letter/b/76d3ee/32.png) [@brian\_j\_murrell](https://community.asterisk.org/u/brian_j_murrell)\
**Post date:** [May 20, 2021, 10:07am UTC](https://community.asterisk.org/t/asterisk-sending-invite-without-an-sdp/88679/1 "2021-05-20T10:07:15Z")

</div>

I am using Asterisk 18.2.2. When I call from one extension to another, the `INVITE` that Asterisk is sending to the called extension is not including any SDP at all:

```auto
<--- Transmitting SIP request (1156 bytes) to TCP:10.75.22.212:37334 --->
INVITE sip:my_sip_account@10.75.22.212:37334;transport=tcp;pn-type=firebase;app-id=[redacted];pn-tok=[redacted];pn-timeout=0;pn-silent=1 SIP/2.0
Via: SIP/2.0/TCP 10.75.22.8:5060;rport;branch=z9hG4bKPj1fa40ba5-8fec-4db3-bcf4-b7720f73678a;alias
From: "[redacted]" <sip:[redacted]@10.75.22.8>;tag=e9c5b70a-8444-45f6-ad2c-2f0a06a1ec80
To: <sip:my_sip_account@10.75.22.212;pn-type=firebase;app-id=[redacted];pn-tok=[redacted];pn-timeout=0;pn-silent=1>
Contact: <sip:asterisk@10.75.22.8:5060;transport=TCP>
Call-ID: 265bf877-b221-45e2-b7b9-33d4193bc027
CSeq: 29228 INVITE
Allow: OPTIONS, REGISTER, SUBSCRIBE, NOTIFY, PUBLISH, INVITE, ACK, BYE, CANCEL, UPDATE, PRACK, MESSAGE, REFER
Supported: 100rel, timer, replaces, norefersub, histinfo
Session-Expires: 1800
Min-SE: 90
Max-Forwards: 70
User-Agent: Asterisk PBX 18.2.2
Content-Length: 0

<--- Received SIP response (566 bytes) from TCP:10.75.22.212:37334 --->
SIP/2.0 100 Trying
Via: SIP/2.0/TCP 10.75.22.8:5060;rport;branch=z9hG4bKPj1fa40ba5-8fec-4db3-bcf4-b7720f73678a;alias
From: "[redacted]" <sip:[redacted]@10.75.22.8>;tag=e9c5b70a-8444-45f6-ad2c-2f0a06a1ec80
To: <sip:my_sip_account@10.75.22.212;pn-type=firebase;app-id==[redacted];pn-tok==[redacted];pn-timeout=0;pn-silent=1>
Call-ID: 265bf877-b221-45e2-b7b9-33d4193bc027
CSeq: 29228 INVITE
Content-Length: 0

```

The call ends up being terminated immediately upon answer by the caller with:

```auto
[May 20 05:31:00] ERROR[4901]: res_pjsip_session.c:902 handle_incoming_sdp: PJSIP/my_sip_account-00000012: Couldn't negotiate stream 0:audio-0:audio:sendrecv (ulaw|opus|codec2|g723|alaw|gsm|g726|g726aal2|adpcm|slin|slin12|slin16|slin24|slin32|slin44|slin48|slin96|slin192|lpc10|g729|speex|speex16|speex32|ilbc|g722|siren7|siren14|testlaw|g719|silk8|silk12|silk16|silk24)   

```

Ultimately the above error and the call terminating are the symptom I am trying to resolve, but the `INVITE` without an SDP seems suspicious. Is it related?

---

<div class="post-metadata">

**Author:** ![david551](https://avatars.discourse-cdn.com/v4/letter/d/3bc359/32.png) [@david551](https://community.asterisk.org/u/david551)\
**Post date:** [May 20, 2021, 10:29am UTC](https://community.asterisk.org/t/asterisk-sending-invite-without-an-sdp/88679/2 "2021-05-20T10:29:21Z")

</div>

This typically happens when the configuration, which you didn’t provide, allows all codecs.

---

<div class="post-metadata">

**Author:** ![brian\_j\_murrell](https://avatars.discourse-cdn.com/v4/letter/b/76d3ee/32.png) [@brian\_j\_murrell](https://community.asterisk.org/u/brian_j_murrell)\
**Post date:** [May 20, 2021, 11:53am UTC](https://community.asterisk.org/t/asterisk-sending-invite-without-an-sdp/88679/3 "2021-05-20T11:53:29Z")

</div>

Wait. Allowing all codecs causes a call to fail? Why would that happen?

But it seems you are correct. Just choosing a codec (more or less at random) and disallowing it seems to have resolved the issue.

That surely is a bug, yes?

---

<div class="post-metadata">

**Author:** ![jcolp](https://sea1.discourse-cdn.com/asterisk/user_avatar/community.asterisk.org/jcolp/32/8848_2.png) [@jcolp](https://community.asterisk.org/u/jcolp)\
**Post date:** [May 20, 2021, 12:02pm UTC](https://community.asterisk.org/t/asterisk-sending-invite-without-an-sdp/88679/4 "2021-05-20T12:02:48Z")

</div>

[https://issues.asterisk.org/jira/browse/ASTERISK-29185](https://issues.asterisk.org/jira/browse/ASTERISK-29185)

---

<div class="post-metadata">

**Author:** ![system](https://global.discourse-cdn.com/asterisk/original/2X/4/475d0c889911cfb84ac4881ad6df8b523e3f9105.png) [@system](https://community.asterisk.org/u/system)\
**Post date:** [June 19, 2021, 12:03pm UTC](https://community.asterisk.org/t/asterisk-sending-invite-without-an-sdp/88679/5 "2021-06-19T12:03:11Z")

</div>

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