How to twin ring mobiles and save money!

Hi all, I have just got to work (with help from a few people!) is a whole bunch of features to work with my mobile phone using a SIP to GSM Gateway and I thought I would share theme here as I haven't seen this level of integration done with a mobile phone on the UC.

What I have is a GSM Gateway with a built in SIP proxy and a free per minute GSM calling plan and a UC500 with V4.3.

What I got working nicely is :
Mobile twining - getting my mobile to ring at the same time with my IP phone by putting them in a group (slight GSM delay)

Busy lamp - when I am on a mobile call via the office, the UC shows me as busy.

Mobile phone transfer - The ability to be on my mobile (calls via the office) and I can transfer and conference them to another extension or trunk number.

DISA - The UC has Disa built in, but all these calls do not appear in the call accounting and CDR. So what I do is call from my mobile to the GSM gateway, the gateway then gives me dial tone of the SIP extension that I associate with my mobile phone and bang!! I call extensions or break out to the outside world at next to nothing.

I found a mobile phone client that directs the call via the GSM gateway, instead of the GSM carrier charging me. We are on a free per min calling plan in our group. So the GSM gateway has one of these SIMs in it!

So far our mobile phone bill has been reduced by about 70% I would say!!!

So all our mobiles in our work place are being directed via the GSM gateway > SIP extension and then out the UC trunks and thats why we needed call accounting on the UC.

To get third party SIP working:
voice service voip
allow-connections h323 to h323
allow-connections h323 to sip
allow-connections sip to h323
allow-connections sip to sip
supplementary-service h450.12
fax protocol none
modem passthrough nse codec g711ulaw
sip
registrar server expires max 1200 min 300
!
voice class codec 1
codec preference 1 g711ulaw
codec preference 2 g729r8
!
voice register global
mode cme
source-address 10.1.1.1 port 5060
max-dn 20
max-pool 10
authenticate register
time-format 24
date-format D/M/Y
voicemail 90
file text
create profile

Repeat the below for each extension that will map to a mobile.

voice register dn 1
number 201
allow watch
name Joe Smith
label 201
mwi
!
voice register pool 1
id mac
number 1 dn 1
dtmf-relay sip-notify
username 40 password 1234

This also saved us from buying the
Unified CallConnector Mobility and server as we don't need to mess around with presence info as you always carry your mobile!