Do I need a new IOS Image for a voice router?

I have two routers I'm trying to setup in a small voice lab so I can create some call legs between them, but one of them doesn't have any voice commands on it. Below are the routers I have:
2611XM - Running IOS: c2600-adventerprisek9-mz.124-15.T14.bin
48MB Flash / 256MB RAM
2621XM - Running IOS: c2600-advsecurityk9-mz.124-19b.bin
32MB Flash / 96MB RAM
The 2611XM was bought off of ebay as a voice router and works just fine, it came with the expansion module (NM-2V). For the 2621XM I picked up a (NM-HD-2V) from ebay. Both (NM-2V) and (NM-HD-2V) cards work fine in the 2611XM, but neither are recognized in the 2621XM.
Do I need to upgrade the IOS Image on the 2621XM for it to recognize either of these cards? There are no voice commands available on this router so I'm assuming I do, but I want to double check with you guys before I start buying more stuff off of ebay
. The current image on the 2611XM won't fit on the 2621XM, so I'm assuming I will also have to upgrade the flash from 32MB to 48MB as well. Anything else I'll need to turn this 2621XM into a voice router?
2611XM - Running IOS: c2600-adventerprisek9-mz.124-15.T14.bin
48MB Flash / 256MB RAM
2621XM - Running IOS: c2600-advsecurityk9-mz.124-19b.bin
32MB Flash / 96MB RAM
The 2611XM was bought off of ebay as a voice router and works just fine, it came with the expansion module (NM-2V). For the 2621XM I picked up a (NM-HD-2V) from ebay. Both (NM-2V) and (NM-HD-2V) cards work fine in the 2611XM, but neither are recognized in the 2621XM.
Do I need to upgrade the IOS Image on the 2621XM for it to recognize either of these cards? There are no voice commands available on this router so I'm assuming I do, but I want to double check with you guys before I start buying more stuff off of ebay

Comments
I usually tend to go with adventerprisek9 image on all my routers, one size fits all tracks then.
It is more $$$ but its not that much in the greater scheme of things, reckon you could fit out a 2801 with an E1/T1 WIC and DSPs for around 6-700 USD, you only need two (its not R&S LOL and you could re-use the hardware for any Cisco track lab) its the virt that kills you (Pub, Sub, CUPS, unity, preferably LDAP/AD), then POE switch and reasonably current phones (7942s though 7940s will prob get you through the exams up to CCNP-V at least). The voice track is defo the most $$$ to lab as you cannot '****' with GNS or IOUs
Right now I'm just trying to get through the basics, I'm not really focused on certification but when I do plan for that I'm going to upgrade. I have a few 3550's, one with power, and 5 7940/60 phones. I also have a Dell PowerEdge 2850 that might be useful for CCNP Voice level, although I worry it might not have enough processing power.
Anyway I found an IOS that fit in my 2821's 32MB of flash, and looks like I'm now good to go with two voice routers
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Currently Studying: CCNP: Wireless - IUWMS
Remember Cisco voice only really gained maturity on the latter versions of 12.4T (around where callmanager v4 came out) so you may be hamstringing yourself if your IOS is too old (and wondering why the commands in the book don't work lol). I remember actually having the glory of 'discovering' bugs with TAC whereas I've never ever hit a bug in R&S that wasn't already existing/known.
Used 1 Cisco 2801 ISR Router 115712K 15360K Memory 64MB Flash Great for CCNA | eBay
That's just one example. I got three of them from a guy a few weeks ago for $80 each. Weird.
Notice the absence of the NM Slot, it only has 4x WIC slots.
Latest blog post: Let's review EIGRP Named Mode
Currently Studying: CCNP: Wireless - IUWMS
I still would prefer an 1841 for R&S lab purposes - smaller, quieter, can still run 15.1M AES, MPLS-VPN, MP-BGP. Once I'm done with CCNP-V I have zero intention of going further down the voice track :P
As far as the 2801 missing an NM slot, it isn't necessary for voice work at all unless you want to shell out the cash for an NM-CUE or something. For voice studies, it's hard to beat the 2801 for the price and capability.
I've never seen a CUCM deployment go to the extra length of deploying NM-CUEs just so SRST also has voicemail. Only ever seen them in CCME deployments = simple config.
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