Question for Voice Engineers in the field

I was approached by a recruiter for an ongoing contract role as a Voice Admin at a huge school something around 50k endpoints. It is basically Admin to CUCM,CUC, Avaya, Polycom (add/remove/call handlers/bat/cti) Basic Admin role. The pay is really generous. My concern is I work more so on a "engineer side". I set up WLC, ASA(vpn, acl, etc), CUCM (50 users), CUC(aa voicemail), CUBE, SIP TRUNKS, Routers (IGP), Switches all in several small businesses up to 75 users. I work more so on the voice side since thats the first thing people realize that they having a problem with. I would like to venture off into the voice side since I feel I have a firm grasp on it. I see this role as possibly taking a step back but on the other side it could give me experience working on a huge environment.
Only reason I'm considering this position because I will have CUCM and exposure to everything else (on the admin side) on a day to day basis in a much larger environment. My concern is I know how these recruiters are already if I take this role and hang out for a year or whatever and try to transition in an Voice engineer role I may run into an wall. I know they'll say, "I see you work more on the Admin side, but we are looking for someone who works with voice gateways/cube mgcp, h323, sip and all of that stuff plus the call routing in cucm.
Any insight to see if this position is a good move?
Only reason I'm considering this position because I will have CUCM and exposure to everything else (on the admin side) on a day to day basis in a much larger environment. My concern is I know how these recruiters are already if I take this role and hang out for a year or whatever and try to transition in an Voice engineer role I may run into an wall. I know they'll say, "I see you work more on the Admin side, but we are looking for someone who works with voice gateways/cube mgcp, h323, sip and all of that stuff plus the call routing in cucm.
Any insight to see if this position is a good move?
Comments
[X] CIPTV2 300-075
[ ] SIP School SSCA
[X] CCNP Switch 300-115 [X] CCNP Route 300-101 [X] CCNP Tshoot 300-135
[ ] LPIC1-101 [ ] LPIC1-102 (wishful thinking)
The learning curve has been huge for me!
In a good way though as I like to be thrown in at the deep end.