### Description
Carrierroute's CRC32 algorithm over call_id tends to produce poor call
distribution under real world examples. Having 4 records for a given
carrier/domain combo (assuming no flags, mask, or scan_prefix) and a
probability of `0.25` using a hash source of `call_id` I observed over 800
hundred consecutive calls from a carrier (bandwidth.com) where `CRC32(call_id)
% 1000` was less than 250.
To be fair, the module does what it says - it uses a CRC32 hash over the call
id, however the data from the UA generating the call is yielding poor results.
Would it be possible to change to an alternate hashing mechanism (or add
another hashing mechanism, selectable via `modparam`) such as MD5?
### Expected behavior
Even distribution across all hosts provided.
#### Actual observed behavior
Uneven distribution under real-world conditions.
#### Debugging Data
I can provide a list of > 800 call-ids observed that all routed to the same
endpoint. These are pulled from real world calls, and while there's not much
danger in just having call-id's I would still prefer not to post it into github
for posterity.
#### Log Messages
Log messages end up looking similar to this. I validated that the number is
the CRC32 hash of the call id, so it's not a bug in the module.
```
proxy-1 | 1(7) DEBUG: carrierroute [cr_func.c:449]: rewrite_on_rule():
searching for matching routing rules 1(7) DEBUG: carrierroute
[prime_hash.c:66]: hash_func(): hash: 2417021133 % 1000 = 133
proxy-1 | 1(7) INFO: carrierroute [cr_func.c:689]: ki_cr_do_route_helper():
uri service was rewritten to sip:service@host-d, carrier 1, domain 1
```
### Possible Solutions
Ability to use MD5, kamailio's core hash function or other such hashing function
### Additional Information
Problem validate in 5.7.3, but since it's *correct* by module design, it
shouldn't have changed in 5.8
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https://github.com/kamailio/kamailio/issues/3786
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