### Description Right now, usrloc keepalive method use a somewhat static call-id, built with the prefix `ksrulka-` followed by the number of keepalives sent and the contact index of each AoR pinged.

This means that pings to different contacts from different processes (when using timer_procs in usrloc) or when you have multiple proxies each handling a subset of registrar requests, you can have duplicated call-ids.

Basically the following happens: - user1 registers to proxy - user2 registers to proxy - different timer processes handles the keepalives - call-ids are the same (it start always from `ksrulka-1.1`)

OR - user1 registers to proxyA - user2 registers to proxyB - both proxies start sending keepalives - call-ids are the same (it start always from `ksrulka-1.1`) from both proxies.

While this is not a routing problem, bug or whatever, it can be annoying if traffic is analyzed with tools like sngrep, which group messages by the Call-ID header, and if you run sngrep on the edge proxy you'll see both keepalive messages under the same call. Can be also annoying if logs from all proxies are aggregated, making a bit problematic filtering by call-id.

### Expected behavior Call-id should be somewhat random.

#### SIP Traffic This is an example for same call-id used for pinging two different AoR on same proxy.

``` 2022/08/23 08:53:35.717668 172.23.42.2:5060 -> 172.23.42.1:5060 OPTIONS sip:user1@192.168.10.123:23045;transport=udp SIP/2.0 Via: SIP/2.0/UDP 172.23.42.2:5060;branch=z9hG4bKx.323.1.0 Route: sip:172.23.42.1;lr;received=sip:client.public.ip:23045;r2=on,sip:kamailio.public.ip;lr;received=sip:client.public.ip:23045;r2=on From: sip:pinger@test.proxy;tag=uloc-1-6304863f-61-2-8a27955a-6304958f-af2a3-143.1 To: sip:user1@example.com Call-ID: ksrulka-323.1 CSeq: 80 OPTIONS Content-Length: 0

``` and

``` 2022/08/23 08:53:35.897076 172.23.42.2:5060 -> 172.23.42.1:5060 OPTIONS sip:user2@192.168.10.130:5060 SIP/2.0 Via: SIP/2.0/UDP 172.23.42.2:5060;branch=z9hG4bKx.323.1.0 Route: sip:172.23.42.1;lr;received=sip:client.public.ip:60058;r2=on,sip:kamailio.public.ip;lr;received=sip:client.public.ip:60058;r2=on From: sip:pinger@test.proxy;tag=uloc-1-6304863f-61-1-86c70e53-6304958f-dafc7-143.1 To: sip:user2@example.com Call-ID: ksrulka-323.1 CSeq: 80 OPTIONS Content-Length: 0 ```

### Possible Solutions To be 100% honest I don't get why such method of generating call-ids has been chosen. The only useful thing I see is that you can have a clue of how many keepalives ping have been sent by each process / proxy while inspecting sip traces. I don't see any usage of the fixed call-id in handling responses. But I may be wrong, since I'm new to kamailio.

What could be done is to add a random string to the call-id, like nathelper does. If this is acceptable, I can try to create a PR for that.

### Additional Information

* **Kamailio Version** - output of `kamailio -v`

``` version: kamailio 5.6.1 (x86_64/linux) flags: USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLOCKLIST, HAVE_RESOLV_RES, TLS_PTHREAD_MUTEX_SHARED ADAPTIVE_WAIT_LOOPS 1024, MAX_RECV_BUFFER_SIZE 262144, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB poll method support: poll, epoll_lt, epoll_et, sigio_rt, select. id: unknown compiled with gcc 9.4.0 ```

* **Operating System**: Using official docker images of kamailio 5.6.1.