#### Pre-Submission Checklist

- [X] Commit message has the format required by CONTRIBUTING guide - [X] Commits are split per component (core, individual modules, libs, utils, ...) - [X] Each component has a single commit (if not, squash them into one commit) - [X] No commits to README files for modules (changes must be done to docbook files in `doc/` subfolder, the README file is autogenerated)

#### Type Of Change - [X] Small bug fix (non-breaking change which fixes an issue) - [ ] New feature (non-breaking change which adds new functionality) - [ ] Breaking change (fix or feature that would change existing functionality)

#### Checklist:

- [ ] PR should be backported to stable branches - [X] Tested changes locally - [ ] Related to issue #XXXX (replace XXXX with an open issue number)

#### Description

While testing Kamailio instance with multiple interfaces I noticed that dispatcher probing does not use the socket defined on dispatcher ```list_file```. By setting flag ```SND_F_FORCE_SOCKET```, in tm module, dispatcher probing or tm t_uac_send() is sourced as per ```socket``` attribute.

Tested on FreeBSD 11.1 and Ubuntu 16.04. You can view, comment on, or merge this pull request online at:

https://github.com/kamailio/kamailio/pull/1451

-- Commit Summary --

* tm: flag core to use forced socket when uac socket is set

-- File Changes --

M src/modules/tm/uac.c (6)

-- Patch Links --

https://github.com/kamailio/kamailio/pull/1451.patch https://github.com/kamailio/kamailio/pull/1451.diff